485BPOS

SEC Registration Nos.

Nos. 811-03334 and 002-75106

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933	¨
Post-Effective Amendment No. 74	x

and/or

REGISTRATION STATEMENT

UNDER

THE INVESTMENT ACT OF 1940

Amendment No. 74 x

Calvert Social Investment Fund

(Exact Name of Registrant as Specified in Charter)

4550 Montgomery Avenue

Bethesda, Maryland 20814

(Address of Principal Executive Offices)

Registrant’s Telephone Number: (301) 951-4800

William M. Tartikoff

4550 Montgomery Avenue

Bethesda, Maryland 20814

(Name and Address of Agent for Service)

It is proposed that this filing will become effective (check appropriate box):

x immediately upon filing pursuant to paragraph (b)

¨ on (date) pursuant to paragraph (b)

¨ 60 days after filing pursuant to paragraph (a)(1)

¨ on (date) pursuant to paragraph (a)(1)

¨ 75 days after filing pursuant to paragraph (a)(2)

¨ on (date) pursuant to paragraph (a)(2) of Rule 485.

EXPLANTORY NOTE

This post-effective amendment is being filed solely to submit exhibits containing risk/return summary information in interactive data format that is identical to the risk/return information filed as part of Post-Effective Amendment No. 73 to this Registration Statement, as filed on January 30, 2013.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all of the requirements for effectiveness of this registration statement under Rule 485(b) under the Securities Act and has duly caused this registration statement to be signed on its behalf by the undersigned, duly authorized, in the City of Bethesda, and State of Maryland on the 13th day of February 2013.

CALVERT SOCIAL INVESTMENT FUND

BY:

            **             

Barbara J. Krumsiek

President and Trustee

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below on the 13^th day of February 2013, by the following persons in the capacities indicated.

Signature	Title
**              D. WAYNE SILBY	TRUSTEE
**              JOHN G. GUFFEY, JR.	TRUSTEE
**              BARBARA J. KRUMSIEK	PRESIDENT AND TRUSTEE
**              RONALD M. WOLFSHEIMER	TREASURER (PRINCIPAL ACCOUNTING OFFICER)
**              REBECCA L. ADAMSON	TRUSTEE
**              RICHARD L. BAIRD, JR.	TRUSTEE
**              JOY V. JONES	TRUSTEE
**              TERRENCE J. MOLLNER	TRUSTEE
**              MILES D. HARPER, III	TRUSTEE
**By: /s/ Lancelot A. King         Lancelot A. King

Executed by Lancelot A. King, Attorney-in-fact on behalf of those indicated, pursuant to Powers of Attorney, incorporated by reference to registrant’s Post-Effective Amendment No. 73, January 30, 2013, accession number 0000356682-13-000002.

Calvert Social Investment Fund

Post-Effective Amendment No. 74

Registration No. 002-75106

EXHIBIT INDEX

Ex-101.ins	XBRL Instance Document
Ex-101.sch	XBRL Taxonomy Extension Schema Document
Ex-101.cal	XBRL Taxonomy Extension Calculation Linkbase Document
Ex-101.lab	XBRL Taxonomy Extension Labels Linkbase
Ex-101.pre	XBRL Taxonomy Extension Presentation Linkbase Document
Ex-101.def	XBRL Taxonomy Extension Definition Linkbase
Ex-101.cal	XBRL Taxonomy Extension Calculation Linkbase

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

CALVERT SOCIAL INVESTMENT FUND

Prospectus Date

rr_ProspectusDate

Jan. 31, 2013

Institutional | Calvert Large Cap Core Portfolio

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

CALVERT LARGE CAP CORE PORTFOLIO*
Class  (Ticker):   I  (CMIIX)

*Formerly named Calvert Enhanced Equity Portfolio.

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide a total return which exceeds the total return of the Russell 1000 Index over a market cycle through investment in securities that meet the Fund’s investment criteria, including financial, sustainability and social responsibility factors.

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

January 31, 2014

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 48% of its portfolio’s average value.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

48.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $1,000,000 in the Fund for the time periods indicated;
• your investment has a 5% return each year;
• the Fund’s operating expenses remain the same; and
• any Calvert expense limitation is in effect for the period indicated in the fee table above.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund employs an active investment strategy and invests primarily in the common stocks of U.S. large-cap companies that meet the Fund’s investment criteria, including financial, sustainability and social responsibility investment factors, using quantitative, fundamental, and macro-economic insights that are designed to identify stocks with the greatest potential to outperform the market. Insights from this stock selection process are enhanced by the Advisor’s fundamental investment research, which seeks to add value by integrating traditional fundamental investment analysis with the Advisor’s proprietary views on critical environmental, sustainability and governance issues. The portfolio construction process seeks to maximize the benefit of these insights while controlling the Fund’s risk profile relative to its benchmark, the Russell 1000 Index, and minimizing transaction costs. The Fund may sell a security when it no longer appears attractive under this process or if it contributes disproportionately to portfolio risk.

The Fund will normally invest at least 80% of its net assets, including borrowings for investment purposes, in the equity securities (common stock) of large capitalization companies. The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy.

The Fund defines large-cap companies as those within the range of market capitalizations of the Russell 1000 Index. The Russell 1000 Index measures the performance of the 1,000 largest U.S. companies based on the float-adjusted market capitalization of the index constituents. The Russell 1000 Index is adjusted, or reconstituted, annually. As of December 31, 2012, the market capitalization of the Russell 1000 Index ranged from $317 million to $500 billion with a weighted median level of $42.9 billion and a weighted average level of $94.3 billion. Although primarily investing in large-cap U.S. companies, the Fund may also invest in mid-cap and small-cap companies. The Fund may not invest more than 25% of its net assets in foreign securities. The Advisor rebalances the Fund as market conditions warrant while attempting to minimize transaction costs and adhere to its long-term investment objective.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.

Stock Market Risk. The market prices of stocks held by the Fund may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition and on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Large-Cap Company Risk. Large-cap companies may be unable to respond quickly to new competitive challenges such as changes in technology, and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Small-Cap and Mid-Cap Company Risk. Prices of small-cap and mid-cap stocks can be more volatile than those of larger, more established companies. Small-cap and mid-cap companies are more likely to have more limited product lines, fewer capital resources and less depth of management than larger companies.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from differences between regulations that apply to U.S. and foreign issuers and markets, and the potential for foreign markets to be less liquid and more volatile than U.S. markets.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class I shares has varied from year to year. The table compares the Fund’s performance over time with that of an index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

No shareholders held Class I shares for the period from January 18, 2002 through April 29, 2005. Performance results for Class I shares for this period reflect the performance of Class A shares at net asset value. Actual Class I share performance would have been higher than Class A share performance because Class I, unlike Class A, has no Rule 12b-1 fees.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart shows how the performance of the Class I shares has varied from year to year.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.calvert.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Calendar Year Total Returns

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/09	17.40	%
Worst Quarter (of periods shown)	12/31/08	-23.72	%

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns
(as of 12/31/12)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Institutional | Calvert Large Cap Core Portfolio | Class I

Risk/Return:

rr_RiskReturnAbstract

Redemption fee (as a % of amount redeemed or exchanged within 7 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.70%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.17%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.87%

Less fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

(0.06%)

^[1]

Net Expenses

rr_NetExpensesOverAssets

0.81%

1 Year

rr_ExpenseExampleYear01

8,270

3 Years

rr_ExpenseExampleYear03

27,155

5 Years

rr_ExpenseExampleYear05

47,633

10 Years

rr_ExpenseExampleYear10

106,702

2003

rr_AnnualReturn2003

23.82%

2004

rr_AnnualReturn2004

9.47%

2005

rr_AnnualReturn2005

10.24%

2006

rr_AnnualReturn2006

13.04%

2007

rr_AnnualReturn2007

(1.14%)

2008

rr_AnnualReturn2008

(38.18%)

2009

rr_AnnualReturn2009

30.44%

2010

rr_AnnualReturn2010

13.63%

2011

rr_AnnualReturn2011

2.76%

2012

rr_AnnualReturn2012

15.01%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter (of periods shown)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

17.40%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter (of periods shown)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(23.72%)

1 Year

rr_AverageAnnualReturnYear01

15.01%

5 Years

rr_AverageAnnualReturnYear05

1.60%

10 Years

rr_AverageAnnualReturnYear10

5.57%

Institutional | Calvert Large Cap Core Portfolio | Return after taxes on distributions | Class I

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

14.80%

5 Years

rr_AverageAnnualReturnYear05

1.40%

10 Years

rr_AverageAnnualReturnYear10

5.24%

Institutional | Calvert Large Cap Core Portfolio | Return after taxes on distributions and sale of Fund shares | Class I

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

10.03%

5 Years

rr_AverageAnnualReturnYear05

1.33%

10 Years

rr_AverageAnnualReturnYear10

4.85%

Institutional | Calvert Large Cap Core Portfolio | Russell 1000 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

16.42%

5 Years

rr_AverageAnnualReturnYear05

1.92%

10 Years

rr_AverageAnnualReturnYear10

7.52%

Institutional | Calvert Large Cap Core Portfolio | Lipper Large-Cap Core Funds Avg. (reflects no deduction for taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

14.95%

5 Years

rr_AverageAnnualReturnYear05

0.68%

10 Years

rr_AverageAnnualReturnYear10

6.51%

[1] The investment advisor has agreed to contractually limit direct net annual fund operating expenses to 0.81% through January 31, 2014. Only the Board of Trustees of the Fund may terminate the Fund's expense limitation before the contractual period expires.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

CALVERT SOCIAL INVESTMENT FUND

Prospectus Date

rr_ProspectusDate

Jan. 31, 2013

Retail | Calvert Bond Portfolio

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

CALVERT BOND PORTFOLIO
Class  (Ticker):   A  (CSIBX)   B  (CBDBX)   C  (CSBCX)   Y  (CSIYX)

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide as high a level of current income as is consistent with prudent investment risk and preservation of capital through investment in bonds and other debt securities meeting the Fund’s investment criteria, including financial, sustainability and social responsibility factors. This objective may be changed by the Fund’s Board of Trustees without shareholder approval.

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 48 and “Reduced Sales Charges” on page 52 of this Prospectus, and under “Method of Distribution” on page 49 of the Fund’s Statement of Additional Information.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 228% of its portfolio’s average value.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

228.00%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

The contingent deferred sales charge reduces over time.

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

50,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;
• your investment has a 5% return each year;
• the Fund’s operating expenses remain the same; and
• any Calvert expense limitation is in effect for the period indicated in the fee table above.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund uses an active strategy, seeking relative value to earn incremental income. Under normal circumstances, the Fund invests at least 80% of its net assets (including borrowings for investment purposes) in bonds. Bonds include debt securities of any maturity. The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy. At least 80% of the Fund’s net assets will be invested in investment grade debt securities. A debt security is investment grade when assigned a credit quality rating of BBB- or higher by Standard & Poor’s Rating Services (“Standard & Poor’s”) or an equivalent rating by another nationally recognized statistical rating organization (‘‘NRSRO”), including Moody’s Investors Service or Fitch Ratings, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.

The Fund invests principally in bonds issued by U.S. corporations, the U.S. government or its agencies, and U.S. government-sponsored entities (e.g., the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”)). The Fund also may invest in trust preferred securities, taxable municipal securities, asset-backed securities (“ABS”), including commercial mortgage-backed securities, and repurchase agreements.

The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include derivative securities such as collateralized mortgage obligations (“CMOs”) and ABS.

In addition, the Fund may invest in leveraged loans. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically.

The Fund may invest up to 20% of its net assets in below-investment grade, high-yield debt securities (commonly known as “junk bonds”), including bonds rated in default. A debt security is below investment grade when assigned a credit quality rating below BBB- by Standard & Poor’s or an equivalent rating by another NRSRO, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.

The Fund may also invest up to 25% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts (“ADRs”).

The Fund is “non-diversified,” which means it may invest a greater percentage of its assets in a particular issuer than a “diversified” fund.

The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Non-Diversification Risk. Because the Fund may invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single stock may have greater impact on the Fund than a diversified fund.

Bond Market Risk. The market prices of bonds held by the Fund may fall.

Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.

Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.

Mortgage-Backed Security Risk (Government-Sponsored Enterprises). Debt and mortgage-backed securities issued by government-sponsored enterprises (“GSEs”) such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.

Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.

Management Risk. The individual investments of the Fund may not perform as expected, due to credit, political or other risks and/or the Fund’s portfolio management practices may not achieve the desired result.

Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.

Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.

Defaulted Bonds Risk. For bonds in default (rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve full recovery.

Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable quality. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of an NRSRO.

Corporate and Taxable Municipal Bond Risk. For corporate and taxable municipal bonds, there is credit risk in addition to the interest rate risk that affects all fixed-income securities.

Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity.

Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and the potential for foreign markets to be less liquid and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.

Repurchase Agreement Risk. A repurchase agreement exposes the Fund to the risk that the party that sells the security may default on its obligation to repurchase it. The Fund may lose money because it cannot sell the security at the agreed-upon time and price or the security loses value before it can be sold.

Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.

Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

Non-Diversification Risk. Because the Fund may invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single stock may have greater impact on the Fund than a diversified fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of an index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

Performance results for Class Y shares prior to October 31, 2008 (the Class Y shares’ inception date) reflect the performance of Class A shares at net asset value. Actual Class Y share performance would have been higher than Class A share performance because Class Y, unlike Class A, has no Rule 12b-1 fees.

The return for each of the Fund’s other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart shows how the performance of the Class A shares has varied from year to year.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.calvert.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Calendar Year Total Returns for Class A at NAV

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/09	5.58	%
Worst Quarter (of periods shown)	12/31/08	-3.66	%

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns
(as of 12-31-12) (with maximum
sales charge deducted, if any)

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Retail | Calvert Bond Portfolio | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

3.75%

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.65%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.20%

Other expenses

rr_OtherExpensesOverAssets

0.31%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.16%

1 Year

rr_ExpenseExampleYear01

489

3 Years

rr_ExpenseExampleYear03

730

5 Years

rr_ExpenseExampleYear05

989

10 Years

rr_ExpenseExampleYear10

1,731

2003

rr_AnnualReturn2003

8.18%

2004

rr_AnnualReturn2004

5.94%

2005

rr_AnnualReturn2005

4.51%

2006

rr_AnnualReturn2006

4.29%

2007

rr_AnnualReturn2007

6.66%

2008

rr_AnnualReturn2008

(5.03%)

2009

rr_AnnualReturn2009

10.86%

2010

rr_AnnualReturn2010

6.17%

2011

rr_AnnualReturn2011

5.60%

2012

rr_AnnualReturn2012

7.67%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter (of periods shown)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

5.58%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter (of periods shown)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(3.66%)

1 Year

rr_AverageAnnualReturnYear01

3.66%

5 Years

rr_AverageAnnualReturnYear05

4.11%

10 Years

rr_AverageAnnualReturnYear10

5.00%

Retail | Calvert Bond Portfolio | Class B

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

4.00%

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.65%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.66%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.31%

1 Year

rr_ExpenseExampleYear01

634

3 Years

rr_ExpenseExampleYear03

921

5 Years

rr_ExpenseExampleYear05

1,235

10 Years

rr_ExpenseExampleYear10

2,090

1 Year

rr_ExpenseExampleNoRedemptionYear01

234

3 Years

rr_ExpenseExampleNoRedemptionYear03

721

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,235

10 Years

rr_ExpenseExampleNoRedemptionYear10

2,090

1 Year

rr_AverageAnnualReturnYear01

2.57%

5 Years

rr_AverageAnnualReturnYear05

3.84%

10 Years

rr_AverageAnnualReturnYear10

4.37%

Retail | Calvert Bond Portfolio | Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

1.00%

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.65%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.31%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.96%

1 Year

rr_ExpenseExampleYear01

299

3 Years

rr_ExpenseExampleYear03

615

5 Years

rr_ExpenseExampleYear05

1,057

10 Years

rr_ExpenseExampleYear10

2,285

1 Year

rr_ExpenseExampleNoRedemptionYear01

199

3 Years

rr_ExpenseExampleNoRedemptionYear03

615

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,057

10 Years

rr_ExpenseExampleNoRedemptionYear10

2,285

1 Year

rr_AverageAnnualReturnYear01

5.85%

5 Years

rr_AverageAnnualReturnYear05

4.08%

10 Years

rr_AverageAnnualReturnYear10

4.54%

Retail | Calvert Bond Portfolio | Class Y

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.65%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.22%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.87%

1 Year

rr_ExpenseExampleYear01

89

3 Years

rr_ExpenseExampleYear03

278

5 Years

rr_ExpenseExampleYear05

482

10 Years

rr_ExpenseExampleYear10

1,073

1 Year

rr_AverageAnnualReturnYear01

7.97%

5 Years

rr_AverageAnnualReturnYear05

5.14%

10 Years

rr_AverageAnnualReturnYear10

5.52%

Retail | Calvert Bond Portfolio | Return after taxes on distributions | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

2.23%

5 Years

rr_AverageAnnualReturnYear05

2.63%

10 Years

rr_AverageAnnualReturnYear10

3.35%

Retail | Calvert Bond Portfolio | Return after taxes on distributions and sale of Fund shares | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

2.38%

5 Years

rr_AverageAnnualReturnYear05

2.64%

10 Years

rr_AverageAnnualReturnYear10

3.33%

Retail | Calvert Bond Portfolio | Barclays U.S. Credit Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

9.37%

5 Years

rr_AverageAnnualReturnYear05

7.65%

10 Years

rr_AverageAnnualReturnYear10

6.23%

Retail | Calvert Bond Portfolio | Lipper Corporate Debt Funds A Rated Avg. (reflects no deduction for taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

7.11%

5 Years

rr_AverageAnnualReturnYear05

6.31%

10 Years

rr_AverageAnnualReturnYear10

5.33%

[1] The contingent deferred sales charge reduces over time.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

CALVERT SOCIAL INVESTMENT FUND

Prospectus Date

rr_ProspectusDate

Jan. 31, 2013

Retail | Calvert Conservative Allocation Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

CALVERT CONSERVATIVE ALLOCATION FUND
Class  (Ticker):   A  (CCLAX)   C  (CALCX)

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks current income and capital appreciation, consistent with the preservation of capital. This objective may be changed by the Fund’s Board of Trustees without shareholder approval.

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 89 and “Reduced Sales Charges” on page 92 of this Prospectus, and under “Method of Distribution” on page 51 of the Fund’s Statement of Additional Information (“SAI”).

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

January 31, 2014

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund may pay transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). These transaction costs are also incurred by the underlying Calvert funds. A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 26% of its portfolio’s average value.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

26.00%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

The contingent deferred sales charge reduces over time.

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

50,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;
• your investment has a 5% return each year;
• the Fund’s operating expenses remain the same;
• any Calvert expense limitation is in effect for the period indicated in the fee table above; and
• the estimated gross expenses of the underlying Calvert funds (or net expenses if subject to an expense limit for at least a year) are incorporated.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that seeks to achieve its investment objective by investing in a portfolio of underlying Calvert fixed-income, equity and money market funds that meets the Fund’s investment criteria, including financial, sustainability and social responsibility factors.

The Fund invests in underlying Calvert funds in accordance with a stable target asset allocation determined by the Advisor. The Fund’s asset allocation strategy incorporates historical risk and return characteristics of various asset classes and correlations between asset classes to establish allocations intended to provide an optimal level of return for a given level of risk. Historical returns-based analysis and actual holdings data of the target underlying Calvert funds are then integrated to blend the styles of the underlying Calvert funds with the asset allocation policy.

The Fund intends to invest in shares of underlying Calvert funds and typically invests in underlying Calvert funds as follows:

60% to 80% of	In Calvert Bond Portfolio (which invests
Fund's net assets	primarily in fixed-income securities)
20% to 40% of	In funds that invest primarily in equity secu-
Fund's net assets	rities (Calvert Equity Portfolio, Calvert
	Social Index Fund, Calvert Large Cap Core
	Portfolio, Calvert Capital Accumulation Fund,
	Calvert International Equity Fund, Calvert
	International Opportunities Fund, Calvert
	Emerging Markets Equity Fund, Calvert
	Global Alternative Energy Fund, Calvert
	Global Water Fund and Calvert Small Cap
	Fund)
0% to 10% of Fund's	In Calvert Money Market Portfolio (which
net assets	invests primarily in money market instruments)

The Fund may also invest, to a limited extent, in (1) derivative instruments, including, but not limited to, index futures, options and swaps; and (2) exchange-traded funds. The Fund will use these instruments to facilitate the periodic rebalancing of the Fund’s portfolio to maintain its target asset allocation, to make tactical asset allocations and to assist in managing cash.

For information on the investment objectives, strategies and risks of the underlying Calvert funds, see the respective Fund Summaries of the underlying equity funds in this Prospectus, and see “Description of Underlying Funds” in this Prospectus, which describes the underlying fixed-income and money market funds (Calvert Bond Portfolio and Calvert Money Market Portfolio).

The Advisor may select new or different underlying Calvert funds other than those listed above without prior approval of or prior notice to shareholders.

The above asset allocation percentages are allocation targets. The Advisor has discretion to reallocate the Fund’s assets among underlying Calvert funds. The Advisor monitors the Fund’s allocation and may rebalance or reallocate the Fund’s assets (1) based on its view of economic and market factors and events or (2) to adjust for shifts in the style biases of the underlying funds. The Advisor also evaluates any necessary rebalancing to reflect different target asset class allocations based on changed economic and market conditions.

Sustainable and Socially Responsible Investing. Each underlying fund (other than Calvert Global Alternative Energy Fund and Calvert Global Water Fund) seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert Global Alternative Energy Fund will invest in ways consistent with Calvert’s philosophy that long-term rewards to investors will come from companies and other entities whose products, services, and methods contribute to a more sustainable future. Calvert Global Water Fund seeks to invest in a wide range of companies and other enterprises that demonstrate varying degrees of commitment and progress toward addressing key corporate responsibility and sustainability challenges.

Each underlying fund (other than Calvert Global Water Fund) has sustainable and socially responsible investment criteria that reflect specific types of companies in which the fund seeks to invest and seeks to avoid investing. Calvert Global Water Fund’s sustainable and socially responsible investment criteria reflect threshold responsibility standards used in determining whether a security qualifies as an investment for the fund, and specific types of companies in which the fund seeks to invest.

Investments for each underlying fund are first selected for financial soundness and then evaluated according to the fund’s sustainable and socially responsible investment criteria. Investments for each underlying fund must be consistent with the fund’s current investment criteria, including financial, sustainability and social responsibility factors, as well as threshold responsibility standards (for Calvert Global Water Fund only), the application of which is in the economic interest of the underlying fund and its shareholders.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Asset Allocation Risk. The Advisor’s selection of underlying funds and the allocation of Fund assets to those funds may cause the Fund to underperform. The Fund’s greater allocation to fixed-income funds makes it more susceptible to risks associated with fixed-income investments than equity investments.

Management Risk. Individual investments of an underlying fund may not perform as expected, and the underlying fund’s portfolio management practices may not achieve the desired result.

Derivatives Risk. In general, a derivative is a financial contract whose value is based on the value of a financial asset (such as a stock, bond, or currency), a physical asset (such as gold), or a market index (such as the S&P 500 Index). Derivative instruments are subject to a number of risks, including the risk of changes in the market price of the underlying asset, credit risk with respect to the counterparty, and liquidity risk. The Fund’s use of certain derivatives may also have a leveraging effect, which may increase the volatility of the Fund and reduce its returns.

Exchange-Traded Fund (“ETF”) Risk. An ETF seeks to track the performance of an index by holding in its portfolio shares of all the companies, or a representative sample of the companies, that are components of a particular index. The risks of investment in ETFs typically reflect the risk of the types of securities in which the ETFs invest. In addition, when the Fund invests in an ETF, shareholders of the Fund bear their proportionate share of the ETF’s fees and expenses as well as their share of the Fund’s fees and expenses.

Equity Investments. The Fund shares the principal risks of equity securities held by the underlying funds, including the key risks below.

Stock Market Risk. The market prices of stocks held by the underlying funds may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Fixed-Income Investments. The Fund shares the principal risks of fixed-income securities held by the underlying funds, including the key risks below.

Bond Market Risk. The market prices of bonds held by the underlying funds may fall.

Interest Rate Risk. A change in interest rates may adversely affect the value of the securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.

Credit Risk. The credit quality of the securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.

Money Market Investments. The Fund shares the principal risks of money market securities held by the underlying funds, including the key risk below.

Money Market Risk. Yield will change in response to market interest rates; in general, as market rates go up, so will yield, and vice versa. Although the underlying fund tries to keep the value of its shares constant at $1.00 per share, changes in market rates could cause the value to decrease. Credit quality of the securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due. Credit risk, however, should be low for the underlying fund because it invests primarily in securities that are considered to be of high quality; the underlying fund also limits the amount it invests in any one issuer to try to lessen its exposure to credit risk.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of a broad-based securities market index, a composite index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

The return for the Fund’s other Class of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart shows how the performance of the Class A shares has varied from year to year.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.calvert.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Calendar Year Total Returns for Class A at NAV

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/09	9.08	%
Worst Quarter (of periods shown)	12/31/08	-9.39	%

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns
(as of 12/31/12) (with maximum
sales charge deducted)

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns are shown only for Class A shares; after-tax returns for the other Class will vary.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for the other Class will vary.

Retail | Calvert Conservative Allocation Fund | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.75%

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Advisory fee

rr_ManagementFeesOverAssets

none

Administrative fee

csif_AdministrativeFees

0.15%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.37%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.65%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.42%

Less fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

(0.33%)

^[2]

Net annual fund operating expenses

rr_NetExpensesOverAssets

1.09%

1 Year

rr_ExpenseExampleYear01

581

3 Years

rr_ExpenseExampleYear03

872

5 Years

rr_ExpenseExampleYear05

1,185

10 Years

rr_ExpenseExampleYear10

2,069

2006

rr_AnnualReturn2006

7.16%

2007

rr_AnnualReturn2007

5.89%

2008

rr_AnnualReturn2008

(16.17%)

2009

rr_AnnualReturn2009

16.33%

2010

rr_AnnualReturn2010

8.56%

2011

rr_AnnualReturn2011

4.41%

2012

rr_AnnualReturn2012

10.61%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter (of periods shown)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

9.08%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter (of periods shown)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(9.39%)

1 Year

rr_AverageAnnualReturnYear01

5.35%

5 Years

rr_AverageAnnualReturnYear05

3.10%

Since Inception

rr_AverageAnnualReturnSinceInception

4.30%

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 29, 2005

Retail | Calvert Conservative Allocation Fund | Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

1.00%

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Advisory fee

rr_ManagementFeesOverAssets

none

Administrative fee

csif_AdministrativeFees

0.15%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.36%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.65%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.16%

Less fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

^[2]

Net annual fund operating expenses

rr_NetExpensesOverAssets

1 Year

rr_ExpenseExampleYear01

319

3 Years

rr_ExpenseExampleYear03

676

5 Years

rr_ExpenseExampleYear05

1,159

10 Years

rr_ExpenseExampleYear10

2,493

1 Year

rr_ExpenseExampleNoRedemptionYear01

219

3 Years

rr_ExpenseExampleNoRedemptionYear03

676

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,159

10 Years

rr_ExpenseExampleNoRedemptionYear10

2,493

1 Year

rr_AverageAnnualReturnYear01

8.48%

5 Years

rr_AverageAnnualReturnYear05

2.82%

Since Inception

rr_AverageAnnualReturnSinceInception

3.67%

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 29, 2005

Retail | Calvert Conservative Allocation Fund | Return after taxes on distributions | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

4.18%

5 Years

rr_AverageAnnualReturnYear05

1.96%

Since Inception

rr_AverageAnnualReturnSinceInception

3.14%

Retail | Calvert Conservative Allocation Fund | Return after taxes on distributions and sale of Fund shares | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

3.94%

5 Years

rr_AverageAnnualReturnYear05

2.05%

Since Inception

rr_AverageAnnualReturnSinceInception

3.08%

Retail | Calvert Conservative Allocation Fund | Barclays U.S. Credit Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

9.37%

5 Years

rr_AverageAnnualReturnYear05

7.65%

Since Inception

rr_AverageAnnualReturnSinceInception

6.41%

Retail | Calvert Conservative Allocation Fund | Conservative Allocation Composite Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

10.70%

^[3]

5 Years

rr_AverageAnnualReturnYear05

4.86%

^[3]

Since Inception

rr_AverageAnnualReturnSinceInception

5.59%

^[3]

Retail | Calvert Conservative Allocation Fund | Lipper Mixed-Asset Target Allocation Conservative Funds Avg. (reflects no deduction for taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

9.36%

5 Years

rr_AverageAnnualReturnYear05

3.84%

Since Inception

rr_AverageAnnualReturnSinceInception

4.68%

[1] The contingent deferred sales charge reduces over time.

[2] The investment advisor has agreed to contractually limit direct ordinary operating expenses through January 31, 2014. This expense limitation does not limit the acquired fund fees and expenses paid indirectly by a shareholder. Direct ordinary operating expenses will not exceed 0.44% for Class A and 2.00% for Class C. Only the Board of Trustees of the Fund may terminate the Fund's expense limitation before the contractual period expires.

[3] The Fund also shows the Conservative Allocation Composite Index (22% Russell 3000 Index; 8% Morgan Stanley Capital International Europe Australasia Far East Global Investable Market Index; 60% Barclays U.S. Credit Index; 10% Barclays 3-month T-Bill Bellwether Index) because it is more consistent with the Fund's portfolio construction process and represents a more accurate reflection of the Fund's anticipated risk and return patterns.

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Calvert Money Market Portfolio

CALVERT MONEY MARKET PORTFOLIO
Class  (Ticker):   O  (CSIXX)

INVESTMENT OBJECTIVE

The Fund seeks to provide the highest level of current income, consistent with liquidity, safety and security of capital, through investment in money market instruments meeting the Fund’s investment criteria, including financial, sustainability and social responsibility factors. This objective may be changed by the Fund’s Board of Trustees without shareholder approval.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Calvert Money Market Portfolio Class O
Maximum sales charge (load) on purchases (as a % of offering price)	none
Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)	none

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Annual Fund Operating Expenses	Calvert Money Market Portfolio Class O
Management fees	0.50%
Distribution and service (12b-1) fees	none
Other expenses	0.34%
Total annual fund operating expenses	0.84%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated;
• your investment has a 5% return each year; and
• the Fund’s operating expenses remain the same.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Calvert Money Market Portfolio Class O	86	268	466	1,037

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

The Fund invests in high quality money market instruments, such as commercial paper, variable rate demand notes, corporate, agency and taxable municipal obligations, and repurchase agreements. All investments must comply with the SEC’s money market fund requirements per Rule 2a-7 of the Investment Company Act of 1940.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Principal Risks

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

Income Risk. The income level of the Fund will fluctuate with changing market conditions and interest rate levels. The income the Fund receives may fall as a result of a decline in interest rates.

Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall.

Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due. Credit risk, however, should be low for the Fund because it invests primarily in securities that are considered to be of high quality. The Fund also limits the amount it invests in any one issuer to try to lessen its exposure to credit risk.

Management Risk. The individual bonds in the Fund may not perform as expected, due to credit, political or other risks and/or the Fund’s portfolio management practices may not achieve the desired result.

Repurchase Agreement Risk. A repurchase agreement exposes the Fund to the risk that the party that sells the security may default on its obligation to repurchase it. The Fund may lose money because it cannot sell the security at the agreed-upon time and price or the security loses value before it can be sold.

Performance

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class O shares has varied from year to year. The table compares the Fund’s performance over time with an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

Calendar Year Total Returns

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/07	1.15	%
Worst Quarter (of periods shown)	3/31/10	0.00	%

Average Annual Total Returns
(as of 12-31-11)

Average Annual Total Returns Calvert Money Market Portfolio	1 Year	5 Years	10 Years
Class O	0.03%	0.60%	1.53%
Lipper Money Market Funds Avg.	0.02%	0.47%	1.45%

For current yield information, call 800-368-2745, or visit Calvert’s website at www.calvert.com.

XML

Institutional | Calvert Equity Portfolio

CALVERT EQUITY PORTFOLIO
Class  (Ticker):   I  (CEYIX)

INVESTMENT OBJECTIVE

The Fund seeks growth of capital through investment in stocks believed to offer opportunities for potential capital appreciation and which meet the Fund’s investment criteria, including financial, sustainability and social responsibility factors. This objective may be changed by the Fund’s Board of Trustees without shareholder approval.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Institutional Calvert Equity Portfolio Class I
Redemption fee (as a % of amount redeemed or exchanged within 7 days of purchase)	2.00%

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Annual Fund Operating Expenses	Institutional Calvert Equity Portfolio Class I
Management fees	0.60%
Distribution and service (12b-1) fees	none
Other expenses	0.07%
Acquired fund fees and expenses	0.01%
Total annual fund operating expenses	0.68%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $1,000,000 in the Fund for the time periods indicated;
• your investment has a 5% return each year; and
• the Fund’s operating expenses remain the same.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Institutional Calvert Equity Portfolio Class I	6,947	21,754	37,868	84,653

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 36% of its portfolio’s average value.

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

The Fund normally invests at least 80% of its net assets, including borrowings for investment purposes, in equity securities (common stock). The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy. The Fund invests primarily in common stocks of U.S. large-cap companies. The Fund defines large-cap companies as those whose market capitalization falls within the range of the Standard & Poor’s (“S&P”) 500 Index. As of December 31, 2012, the market capitalization of the S&P 500 Index companies ranged from $1.63 billion to $500 billion with a weighted median level of $56.8 billion and a weighted average level of $106.1 billion.

The Fund normally seeks to have a weighted average market capitalization of at least $20 billion.

The Fund may also invest in mid-cap stocks and may invest up to 25% of its net assets in foreign stocks.

The Subadvisor looks for established companies with a history of steady earnings growth. The Subadvisor selects companies based on its opinion that the company has the ability to sustain growth through high profitability and that the stock is favorably priced with respect to those growth expectations.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Principal Risks

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.

Stock Market Risk. The market prices of stocks held by the Fund may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Large-Cap Company Risk. Large-cap companies may be unable to respond quickly to new competitive challenges such as changes in technology, and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Mid-Cap Company Risk. Prices of mid-cap stocks can be more volatile than those of larger, more established companies. Mid-cap companies are more likely to have more limited product lines, fewer capital resources and less depth of management than larger companies.

Growth Company Risk. Prices of growth company securities may fall more than the overall equity markets due to changing economic, political or market conditions or disappointing growth company earnings results. Growth stocks also generally lack the dividends of some value stocks that can cushion stock prices in a falling market.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from differences between regulations that apply to U.S. and foreign issuers and markets, and the potential for foreign markets to be less liquid and more volatile than U.S. markets.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall.

Performance

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class I shares has varied from year to year. The table compares the Fund’s performance over time with that of an index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

Calendar Year Total Returns

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	6/30/09	18.18	%
Worst Quarter (of periods shown)	12/31/08	-24.28	%

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Average Annual Total Returns
(as of 12/31/12)

Average Annual Total Returns Institutional Calvert Equity Portfolio	1 Year	5 Years	10 Years
Class I	16.14%	3.20%	7.08%
Class I Return after taxes on distributions	16.10%	2.80%	6.69%
Class I Return after taxes on distributions and sale of Fund shares	10.55%	2.64%	6.17%
S&P 500 Index (reflects no deduction for fees, expenses or taxes)	16.00%	1.66%	7.10%
Lipper Large-Cap Growth Funds Avg. (reflects no deduction for taxes)	15.26%	1.19%	6.67%

XML

Institutional | Calvert Bond Portfolio

CALVERT BOND PORTFOLIO
Class (Ticker):    I (CBDIX)

INVESTMENT OBJECTIVE

The Fund seeks to provide as high a level of current income as is consistent with prudent investment risk and preservation of capital through investment in bonds and other debt securities meeting the Fund’s investment criteria, including financial, sustainability and social responsibility factors. This objective may be changed by the Fund's Board of Trustees without shareholder approval.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Institutional Calvert Bond Portfolio Class I
Redemption fee (as a % of amount redeemed or exchanged within 7 days of purchase)	2.00%

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Annual Fund Operating Expenses	Institutional Calvert Bond Portfolio Class I
Management fees	0.45%
Distribution and service (12b-1) fees	none
Other expenses	0.11%
Total annual fund operating expenses	0.56%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $1,000,000 in the Fund for the time periods indicated;
• your investment has a 5% return each year; and
• the Fund’s operating expenses remain the same.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Institutional Calvert Bond Portfolio Class I	5,724	17,947	31,279	70,146

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 228% of its portfolio’s average value.

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

The Fund uses an active strategy, seeking relative value to earn incremental income. Under normal circumstances, the Fund invests at least 80% of its net assets (including borrowings for investment purposes) in bonds. Bonds include debt securities of any maturity. The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy. At least 80% of the Fund’s net assets will be invested in investment grade debt securities. A debt security is investment grade when assigned a credit quality rating of BBB- or higher by Standard & Poor’s Ratings Services ("Standard & Poor's") or an equivalent rating by another nationally recognized statistical rating organization (‘‘NRSRO”), including Moody’s Investors Service or Fitch Ratings, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.

The Fund invests principally in bonds issued by U.S. corporations, the U.S. Government or its agencies, and U.S. government-sponsored enterprises (e.g., the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”)). The Fund also may invest in trust preferred securities, taxable municipal securities, asset-backed securities (“ABS”), including commercial mortgage-backed securities, and repurchase agreements.

The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include derivative securities such as collateralized mortgage obligations (“CMOs”) and ABS.

In addition, the Fund may invest in leveraged loans. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically.

The Fund may invest up to 20% of its net assets in below-investment grade, high-yield debt securities (commonly known as “junk bonds”), including bonds rated in default. A debt security is below investment grade when assigned a credit quality rating below BBB- by Standard & Poor’s or an equivalent rating by another NRSRO, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.

The Fund may also invest up to 25% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts (“ADRs”).

The Fund is “non-diversified,” which means it may invest a greater percentage of its assets in a particular issuer than a “diversified” fund.

The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Principal Risks

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Non-Diversification Risk. Because the Fund may invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than a diversified fund.

Bond Market Risk. The market prices of bonds held by the Fund may fall.

Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.

Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.

Mortgage-Backed Security Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by government-sponsored enterprises (“GSEs”) such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. Government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.

Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.

Management Risk. The individual investments of the Fund may not perform as expected, due to credit, political or other risks and/ or the Fund’s portfolio management practices may not achieve the desired result.

Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.

Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.

Defaulted Bonds Risk. For bonds in default (rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve full recovery.

Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable quality. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of an NRSRO.

Corporate and Taxable Municipal Bond Risk. For corporate and taxable municipal bonds, there is credit risk in addition to the interest rate risk that affects all fixed-income securities.

Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity. There can be no assurance as to the liquidity of trust preferred securities and the ability of holders of such securities to sell their holdings.

Asset-Backed Security Risk. The value of investments in asset-backed securities is subject to interest rate risk and credit risk. Asset-backed securities are also subject to prepayment risk and extension risk.

Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and the potential for foreign markets to be less liquid and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.

Repurchase Agreement Risk. A repurchase agreement exposes the Fund to the risk that the party that sells the security may default on its obligation to repurchase it. The Fund may lose money because it cannot sell the security at the agreed-upon time and price or the security loses value before it can be sold.

Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.

Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts.

Performance

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class I shares has varied from year to year. The table compares the Fund’s performance over time with that of an index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

Calendar Year Total Return

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/09	5.73	%
Worst Quarter (of periods shown)	12/31/08	-3.55	%

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Average Annual Total Returns
(as of 12-31-12)

Average Annual Total Returns Institutional Calvert Bond Portfolio	1 Year	5 Years	10 Years
Class I	8.27%	5.53%	6.02%
Class I Return after taxes on distributions	6.54%	3.81%	4.14%
Class I Return after taxes on distributions and sale of Fund shares	5.37%	3.71%	4.08%
Barclays U.S. Credit Index (reflects no deduction for fees, expenses or taxes)	9.37%	7.65%	6.23%
Lipper Corporate Debt Funds A Rated Average (reflects no deduction for taxes)	7.11%	6.31%	5.33%

XML

Retail | Calvert Bond Portfolio

CALVERT BOND PORTFOLIO
Class  (Ticker):   A  (CSIBX)   B  (CBDBX)   C  (CSBCX)   Y  (CSIYX)

INVESTMENT OBJECTIVE

The Fund seeks to provide as high a level of current income as is consistent with prudent investment risk and preservation of capital through investment in bonds and other debt securities meeting the Fund’s investment criteria, including financial, sustainability and social responsibility factors. This objective may be changed by the Fund’s Board of Trustees without shareholder approval.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 48 and “Reduced Sales Charges” on page 52 of this Prospectus, and under “Method of Distribution” on page 49 of the Fund’s Statement of Additional Information.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Retail Calvert Bond Portfolio		Class A	Class B	Class C	Class Y
Maximum sales charge (load) on purchases (as a % of offering price)		3.75%	none	none	none
Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)	[1]	none	4.00%	1.00%	none
Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)		2.00%	2.00%	2.00%	2.00%

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Annual Fund Operating Expenses Retail Calvert Bond Portfolio	Class A	Class B	Class C	Class Y
Management fees	0.65%	0.65%	0.65%	0.65%
Distribution and service (12b-1) fees	0.20%	1.00%	1.00%	none
Other expenses	0.31%	0.66%	0.31%	0.22%
Total annual fund operating expenses	1.16%	2.31%	1.96%	0.87%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;
• your investment has a 5% return each year;
• the Fund’s operating expenses remain the same; and
• any Calvert expense limitation is in effect for the period indicated in the fee table above.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Expense Example Retail Calvert Bond Portfolio (USD $)	1 Year	3 Years	5 Years	10 Years
Class A	489	730	989	1,731
Class B	634	921	1,235	2,090
Class C	299	615	1,057	2,285
Class Y	89	278	482	1,073

Expense Example, No Redemption Retail Calvert Bond Portfolio (USD $)	1 Year	3 Years	5 Years	10 Years
Class B	234	721	1,235	2,090
Class C	199	615	1,057	2,285

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 228% of its portfolio’s average value.

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

The Fund uses an active strategy, seeking relative value to earn incremental income. Under normal circumstances, the Fund invests at least 80% of its net assets (including borrowings for investment purposes) in bonds. Bonds include debt securities of any maturity. The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy. At least 80% of the Fund’s net assets will be invested in investment grade debt securities. A debt security is investment grade when assigned a credit quality rating of BBB- or higher by Standard & Poor’s Rating Services (“Standard & Poor’s”) or an equivalent rating by another nationally recognized statistical rating organization (‘‘NRSRO”), including Moody’s Investors Service or Fitch Ratings, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.

The Fund invests principally in bonds issued by U.S. corporations, the U.S. government or its agencies, and U.S. government-sponsored entities (e.g., the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”)). The Fund also may invest in trust preferred securities, taxable municipal securities, asset-backed securities (“ABS”), including commercial mortgage-backed securities, and repurchase agreements.

The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include derivative securities such as collateralized mortgage obligations (“CMOs”) and ABS.

In addition, the Fund may invest in leveraged loans. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically.

The Fund may invest up to 20% of its net assets in below-investment grade, high-yield debt securities (commonly known as “junk bonds”), including bonds rated in default. A debt security is below investment grade when assigned a credit quality rating below BBB- by Standard & Poor’s or an equivalent rating by another NRSRO, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.

The Fund may also invest up to 25% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts (“ADRs”).

The Fund is “non-diversified,” which means it may invest a greater percentage of its assets in a particular issuer than a “diversified” fund.

The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Principal Risks

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Non-Diversification Risk. Because the Fund may invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single stock may have greater impact on the Fund than a diversified fund.

Bond Market Risk. The market prices of bonds held by the Fund may fall.

Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.

Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.

Mortgage-Backed Security Risk (Government-Sponsored Enterprises). Debt and mortgage-backed securities issued by government-sponsored enterprises (“GSEs”) such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.

Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.

Management Risk. The individual investments of the Fund may not perform as expected, due to credit, political or other risks and/or the Fund’s portfolio management practices may not achieve the desired result.

Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.

Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.

Defaulted Bonds Risk. For bonds in default (rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve full recovery.

Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable quality. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of an NRSRO.

Corporate and Taxable Municipal Bond Risk. For corporate and taxable municipal bonds, there is credit risk in addition to the interest rate risk that affects all fixed-income securities.

Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity.

Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and the potential for foreign markets to be less liquid and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.

Repurchase Agreement Risk. A repurchase agreement exposes the Fund to the risk that the party that sells the security may default on its obligation to repurchase it. The Fund may lose money because it cannot sell the security at the agreed-upon time and price or the security loses value before it can be sold.

Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.

Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts.

Performance

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of an index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

Performance results for Class Y shares prior to October 31, 2008 (the Class Y shares’ inception date) reflect the performance of Class A shares at net asset value. Actual Class Y share performance would have been higher than Class A share performance because Class Y, unlike Class A, has no Rule 12b-1 fees.

The return for each of the Fund’s other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Calendar Year Total Returns for Class A at NAV

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/09	5.58	%
Worst Quarter (of periods shown)	12/31/08	-3.66	%

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Average Annual Total Returns
(as of 12-31-12) (with maximum
sales charge deducted, if any)

Average Annual Total Returns Retail Calvert Bond Portfolio	1 Year	5 Years	10 Years
Class A	3.66%	4.11%	5.00%
Class A Return after taxes on distributions	2.23%	2.63%	3.35%
Class A Return after taxes on distributions and sale of Fund shares	2.38%	2.64%	3.33%
Class B	2.57%	3.84%	4.37%
Class C	5.85%	4.08%	4.54%
Class Y	7.97%	5.14%	5.52%
Barclays U.S. Credit Index (reflects no deduction for fees, expenses or taxes)	9.37%	7.65%	6.23%
Lipper Corporate Debt Funds A Rated Avg. (reflects no deduction for taxes)	7.11%	6.31%	5.33%

[1] The contingent deferred sales charge reduces over time.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

CALVERT SOCIAL INVESTMENT FUND

Prospectus Date

rr_ProspectusDate

Jan. 31, 2013

Retail | Calvert Large Cap Core Portfolio

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

CALVERT LARGE CAP CORE PORTFOLIO*
Class  (Ticker):   A  (CMIFX)   B  (CDXBX)   C  (CMICX)

*Formerly named Calvert Enhanced Equity Portfolio.

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide a total return which exceeds the total return of the Russell 1000 Index over a market cycle through investment in securities that meet the Fund’s investment criteria, including financial, sustainability and social responsibility factors.

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 89 and “Reduced Sales Charges” on page 92 of this Prospectus, and under “Method of Distribution” on page 58 of the Fund’s Statement of Additional Information (“SAI”).

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as
a % of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 48% of its portfolio’s average value.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

48.00%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

The contingent deferred sales charge reduces over time.

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

50,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;
• your investment has a 5% return each year; and
• the Fund’s operating expenses remain the same.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund employs an active investment strategy and invests primarily in the common stocks of U.S. large-cap companies that meet the Fund’s investment criteria, including financial, sustainability and social responsibility investment factors, using quantitative, fundamental, and macro-economic insights that are designed to identify stocks with the greatest potential to outperform the market. Insights from this stock selection process are enhanced by the Advisor’s fundamental investment research, which seeks to add value by integrating traditional fundamental investment analysis with the Advisor’s proprietary views on critical environmental, sustainability and governance issues. The portfolio construction process seeks to maximize the benefit of these insights while controlling the Fund’s risk profile relative to its benchmark, the Russell 1000 Index, and minimizing transaction costs. The Fund may sell a security when it no longer appears attractive under this process or if it contributes disproportionately to portfolio risk.

The Fund will normally invest at least 80% of its net assets, including borrowings for investment purposes, in the equity securities (common stock) of large capitalization companies.

*Formerly named Calvert Enhanced Equity Portfolio.

The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy.

The Fund defines large-cap companies as those within the range of market capitalizations of the Russell 1000 Index. The Russell 1000 Index measures the performance of the 1,000 largest U.S. companies based on the float-adjusted market capitalization of the index constituents. The Russell 1000 Index is adjusted, or reconstituted, annually. As of December 31, 2012, the market capitalization of the Russell 1000 Index ranged from $317 million to $500 billion with a weighted median level of $42.9 billion and a weighted average level of $94.3 billion. Although primarily investing in large-cap U.S. companies, the Fund may also invest in mid-cap and small-cap companies. The Fund may not invest more than 25% of its net assets in foreign securities. The Advisor rebalances the Fund as market conditions warrant while attempting to minimize transaction costs and adhere to its long-term investment objective.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.

Stock Market Risk. The market prices of stocks held by the Fund may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors' perception of a company's well-being.

Large-Cap Company Risk. Large-cap companies may be unable to respond quickly to new competitive challenges such as changes in technology, and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Small-Cap and Mid-Cap Company Risk. Prices of small-cap and mid-cap stocks can be more volatile than those of larger, more established companies. Small-cap and mid-cap companies are more likely to have more limited product lines, fewer capital resources and less depth of management than larger companies.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from differences between regulations that apply to U.S. and foreign issuers and markets, and the potential for foreign markets to be less liquid and more volatile than U.S. markets.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of an index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

The return for each of the Fund’s other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart shows how the performance of the Class A shares has varied from year to year.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.calvert.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Calendar Year Total Returns for Class A at NAV

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/09	17.31	%
Worst Quarter (of periods shown)	12/31/08	-23.84	%

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns
(as of 12/31/12) (with maximum
sales charge deducted)

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Retail | Calvert Large Cap Core Portfolio | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.75%

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.75%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.40%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.40%

1 Year

rr_ExpenseExampleYear01

611

3 Years

rr_ExpenseExampleYear03

897

5 Years

rr_ExpenseExampleYear05

1,204

10 Years

rr_ExpenseExampleYear10

2,075

2003

rr_AnnualReturn2003

23.82%

2004

rr_AnnualReturn2004

9.47%

2005

rr_AnnualReturn2005

4.80%

2006

rr_AnnualReturn2006

12.67%

2007

rr_AnnualReturn2007

(1.65%)

2008

rr_AnnualReturn2008

(38.54%)

2009

rr_AnnualReturn2009

29.58%

2010

rr_AnnualReturn2010

13.00%

2011

rr_AnnualReturn2011

2.21%

2012

rr_AnnualReturn2012

14.39%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter (of periods shown)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

17.31%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter (of periods shown)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(23.84%)

1 Year

rr_AverageAnnualReturnYear01

8.94%

5 Years

rr_AverageAnnualReturnYear05

0.05%

10 Years

rr_AverageAnnualReturnYear10

4.66%

Retail | Calvert Large Cap Core Portfolio | Class B

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

5.00%

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.75%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

1.20%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.95%

1 Year

rr_ExpenseExampleYear01

798

3 Years

rr_ExpenseExampleYear03

1,313

5 Years

rr_ExpenseExampleYear05

1,752

10 Years

rr_ExpenseExampleYear10

2,904

1 Year

rr_ExpenseExampleNoRedemptionYear01

298

3 Years

rr_ExpenseExampleNoRedemptionYear03

913

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,552

10 Years

rr_ExpenseExampleNoRedemptionYear10

2,904

1 Year

rr_AverageAnnualReturnYear01

7.85%

5 Years

rr_AverageAnnualReturnYear05

(0.47%)

10 Years

rr_AverageAnnualReturnYear10

4.01%

Retail | Calvert Large Cap Core Portfolio | Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

1.00%

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.75%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.51%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.26%

1 Year

rr_ExpenseExampleYear01

329

3 Years

rr_ExpenseExampleYear03

706

5 Years

rr_ExpenseExampleYear05

1,210

10 Years

rr_ExpenseExampleYear10

2,595

1 Year

rr_ExpenseExampleNoRedemptionYear01

229

3 Years

rr_ExpenseExampleNoRedemptionYear03

706

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,210

10 Years

rr_ExpenseExampleNoRedemptionYear10

2,595

1 Year

rr_AverageAnnualReturnYear01

12.41%

5 Years

rr_AverageAnnualReturnYear05

0.12%

10 Years

rr_AverageAnnualReturnYear10

4.24%

Retail | Calvert Large Cap Core Portfolio | Return after taxes on distributions | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

8.80%

5 Years

rr_AverageAnnualReturnYear05

(0.09%)

10 Years

rr_AverageAnnualReturnYear10

4.37%

Retail | Calvert Large Cap Core Portfolio | Return after taxes on distributions and sale of Fund shares | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

6.00%

5 Years

rr_AverageAnnualReturnYear05

0.01%

10 Years

rr_AverageAnnualReturnYear10

4.04%

Retail | Calvert Large Cap Core Portfolio | Russell 1000 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

16.42%

5 Years

rr_AverageAnnualReturnYear05

1.92%

10 Years

rr_AverageAnnualReturnYear10

7.52%

Retail | Calvert Large Cap Core Portfolio | Lipper Large-Cap Core Funds Avg. (reflects no deduction for taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

14.95%

5 Years

rr_AverageAnnualReturnYear05

0.68%

10 Years

rr_AverageAnnualReturnYear10

6.51%

[1] The contingent deferred sales charge reduces over time.

XML

Institutional | Calvert Balanced Portfolio

CALVERT BALANCED PORTFOLIO
Class   (Ticker):   I  (CBAIX)

INVESTMENT OBJECTIVE

The Fund seeks to achieve a competitive total return through an actively managed portfolio of stocks, bonds, and money market instruments which offer income and capital growth opportunity and which satisfy the investment criteria, including financial, sustainability and social responsibility factors. This objective may be changed by the Fund’s Board of Trustees without shareholder approval.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Institutional Calvert Balanced Portfolio Class I
Redemption fee (as a % of amount redeemed or exchanged within 7 days of purchase)	2.00%

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Annual Fund Operating Expenses		Institutional Calvert Balanced Portfolio Class I
Management fees		0.55%
Distribution and service (12b-1) fees		none
Other expenses		0.28%
Acquired fund fees and expenses		0.02%
Total annual fund operating expenses		0.85%
Less fee waiver and/or expense reimbursement	[1]	(0.11%)
Net Expenses		0.74%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $1,000,000 in the Fund for the time periods indicated;
• your investment has a 5% return each year;
• the Fund’s operating expenses remain the same; and
• any Calvert expense limitation is in effect for the period indicated in the fee table above.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Institutional Calvert Balanced Portfolio Class I	7,558	26,025	46,057	103,880

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 145% of its portfolio’s average value.

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

The Fund typically invests about 60% of its net assets in stocks and 40% in bonds or other fixed-income investments. Stock investments are primarily common stock in large-cap companies. Fixed-income investments are primarily a wide variety of investment grade debt securities, such as corporate debt securities, mortgage-backed securities (including commercial mortgage-backed securities and collateralized mortgage obligations (“CMOs”)), and other asset-backed securities (“ABS”). The Fund invests in debt and mortgage-backed securities issued by government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”). The Fund may also invest in repurchase agreements.

An investment grade debt security is rated BBB- or higher by a nationally recognized statistical rating organization (“NRSRO”), or is an unrated bond determined by the Advisor to be of comparable credit quality. The Fund may also invest in unrated debt securities.

The Fund invests in a combination of stocks, bonds and money market instruments in an attempt to provide a complete investment portfolio in a single product. The Advisor monitors the Fund’s allocation and may rebalance or reallocate the Fund’s assets based on its view of economic and market factors and events. The equity portion of the Fund is primarily a large cap core U.S. domestic portfolio, although the Fund may also invest in foreign stocks and mid-cap stocks. The equity portion of the Fund seeks companies that have the potential to outperform the market through exceptional growth and/or valuation improvement. The fixed-income portion of the Fund reflects an active trading strategy, seeking total return.

The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund.

The Fund may also use futures contracts as a substitute for direct investment in a particular asset class, in order to facilitate the periodic rebalancing of the Fund’s portfolio to maintain its target asset allocation, to make tactical asset allocations and to assist in managing cash.

The Subadvisors select the equity investments, while the Advisor manages the fixed-income assets and determines the overall asset class mix for the Fund depending upon its view of market conditions and economic outlook.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Principal Risks

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result. There is a risk that the Advisor may allocate assets to an asset class that underperforms other asset classes.

Stock Market Risk. The market prices of stocks held by the Fund may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Large-Cap Company Risk. Large-cap companies may be unable to respond quickly to new competitive challenges such as changes in technology, and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Mid-Cap Company Risk. Prices of mid-cap stocks can be more volatile than those of larger, more established companies. Mid-cap companies are more likely to have more limited product lines, fewer capital resources and less depth of management than larger companies.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from differences between regulations that apply to U.S. and foreign issuers and markets, and the potential for foreign markets to be less liquid and more volatile than U.S. markets.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall.

Bond Market Risk. The market prices of bonds held by the Fund may fall.

Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.

Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.

Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.

Mortgage-Backed Securities Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by GSEs such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. Government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.

Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.

Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable quality. The Fund’s purchase of unrated securities depends on the Advisor’s analysis of credit risk without the assessment of an NRSRO.

Active Trading Strategy Risk. The fixed-income portion of the Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.

Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts.

Repurchase Agreement Risk. A repurchase agreement exposes the fixed-income portion of the Fund to the risk that the party that sells the security may default on its obligation to repurchase it. The Fund may lose money because it cannot sell the security at the agreed-upon time and price or the security loses value before it can be sold.

Performance

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class I shares has varied from year to year. The table compares the Fund’s performance over time with that of a broad-based securities market index, a composite index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

No shareholders held Class I shares for the period from June 30, 2003 through December 27, 2004. Performance results for Class I shares for this period reflect the performance of Class A shares at net asset value. Actual Class I share performance would have been higher than Class A share performance because Class I, unlike Class A, has no Rule 12b-1 fees.

Calendar Year Total Returns

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/09	11.60	%
Worst Quarter (of periods shown)	12/31/08	-18.11	%

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Average Annual Total Returns
(as of 12/31/12)

Average Annual Total Returns Institutional Calvert Balanced Portfolio		1 Year	5 Years	10 Years
Class I		11.38%	2.78%	5.69%
Class I Return after taxes on distributions		11.18%	2.40%	5.21%
Class I Return after taxes on distributions and sale of Fund shares		7.66%	2.22%	4.80%
Russell 1000 Index (reflects no deduction for fees, expenses or taxes)		16.42%	1.92%	7.52%
Balanced Composite Index (reflects no deduction for fees, expenses or taxes)	[1]	13.60%	4.21%	7.01%
Lipper Mixed-Asset Target Allocation Growth Funds Avg. (reflects no deduction for taxes)		12.63%	1.72%	6.48%

[1] The investment advisor has agreed to contractually limit direct net annual fund operating expenses to 0.72% through January 31, 2014. This expense limitation does not limit the acquired fund fees and expenses paid indirectly by a shareholder. Only the Board of Trustees of the Fund may terminate the Fund's expense limitation before the contractual period expires.

[1] The Fund also shows the Balanced Composite Index (60% Russell 1000 Index; 40% Barclays U.S. Credit Index) because it is more consistent with the Fund's portfolio construction process and represents a more accurate reflection of the Fund's anticipated risk and return patterns.

XML

Retail | Calvert Aggressive Allocation Fund

CALVERT AGGRESSIVE ALLOCATION FUND
Class  (Ticker):   A  (CAAAX)   C  (CAACX)

INVESTMENT OBJECTIVE

The Fund seeks long-term capital appreciation. This objective may be changed by the Fund's Board of Trustees without shareholder approval.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 89 and “Reduced Sales Charges” on page 92 of this Prospectus, and under “Method of Distribution” on page 51 of the Fund’s Statement of Additional Information (“SAI”).

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Retail Calvert Aggressive Allocation Fund		Class A	Class C
Maximum sales charge (load) on purchases (as a % of offering price)		4.75%	none
Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)	[1]	none	1.00%
Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)		2.00%	2.00%

Annual Fund Operating Expenses (expenses that you pay each year as a


% of the value of your investment)

Annual Fund Operating Expenses Retail Calvert Aggressive Allocation Fund

Class A

Class C

Advisory fee

none

none

Administrative fee

0.15

0.15

Distribution and service (12b-1) fees

0.25%

1.00%

Other expenses

0.46%

0.54%

Acquired fund fees and expenses

0.82%

0.82%

Total annual fund operating expenses

1.68%

2.51%

Less fee waiver and/or expense reimbursement

^[1]

(0.43%)

Net Expenses

1.25%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;

• your investment has a 5% return each year;

• the Fund’s operating expenses remain the same;

• any Calvert expense limitation is in effect for the period indicated in the fee table above; and

• the estimated gross expenses of the underlying Calvert funds (or net expenses if subject to an expense limit for at least a year) are incorporated.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Expense Example Retail Calvert Aggressive Allocation Fund (USD $)	1 Year	3 Years	5 Years	10 Years
Class A	596	939	1,306	2,333
Class C	354	782	1,335	2,846

Expense Example, No Redemption (USD $)	1 Year	3 Years	5 Years	10 Years
Retail Calvert Aggressive Allocation Fund Class C	254	782	1,335	2,846

Portfolio Turnover

The Fund may pay transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). These transaction costs are also incurred by the underlying Calvert funds. A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 24% of its portfolio’s average value.

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

The Fund is a “fund of funds” that seeks to achieve its investment objective by investing in a portfolio of underlying Calvert fixed-income, equity and money market funds that meets the Fund’s investment criteria, including financial, sustainability and social responsibility factors.

The Fund invests in underlying Calvert funds in accordance with a stable target asset allocation determined by the Advisor. The Fund’s asset allocation strategy incorporates historical risk and return characteristics of various asset classes and correlations between asset classes to establish allocations intended to provide an optimal level of return for a given level of risk. Historical returns-based analysis and actual holdings data of the target underlying Calvert funds are then integrated to blend the styles of the underlying Calvert funds with the asset allocation policy.

The Fund intends to invest in shares of underlying Calvert funds and typically invests in underlying Calvert funds as follows:

80% to 100% of	In funds that invest primarily in equity secu-
Fund's net assets	rities (Calvert Equity Portfolio, Calvert
	Social Index Fund, Calvert Large Cap Core
	Portfolio, Calvert Capital Accumulation Fund,
	Calvert International Equity Fund, Calvert
	International Opportunities Fund, Calvert
	Emerging Markets Equity Fund, Calvert
	Global Alternative Energy Fund, Calvert
	Global Water Fund and Calvert Small Cap
	Fund)
0% to 20% of	In Calvert Bond Portfolio (which invests pri-
Fund's net assets	marily in fixed-income securities)
0% to 5% of Fund's	In Calvert Money Market Portfolio (which
net assets	invests primarily in money market instruments)

The Fund may also invest, to a limited extent, in (1) derivative instruments, including, but not limited to, index futures, options and swaps; and (2) exchange-traded funds. The Fund will use these instruments to facilitate the periodic rebalancing of the Fund’s portfolio to maintain its target asset allocation, to make tactical asset allocations and to assist in managing cash.

For information on the investment objectives, strategies and risks of the underlying Calvert funds, see the respective Fund Summaries of the underlying equity funds in this Prospectus, and see “Description of Underlying Funds” in this Prospectus, which describes the underlying fixed-income and money market funds (Calvert Bond Portfolio and Calvert Money Market Portfolio).

The Advisor may select new or different underlying Calvert funds other than those listed above without prior approval of or prior notice to shareholders.

The above asset allocation percentages are allocation targets. The Advisor has discretion to reallocate the Fund’s assets among underlying Calvert funds. The Advisor monitors the Fund’s allocation and may rebalance or reallocate the Fund’s assets (1) based on its view of economic and market factors and events or (2) to adjust for shifts in the style biases of the underlying funds. The Advisor also evaluates any necessary rebalancing to reflect different target asset class allocations based on changed economic and market conditions.

Sustainable and Socially Responsible Investing. Each underlying fund (other than Calvert Global Alternative Energy Fund and Calvert Global Water Fund) seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert Global Alternative Energy Fund will invest in ways consistent with Calvert’s philosophy that long-term rewards to investors will come from companies and other entities whose products, services, and methods contribute to a more sustainable future. Calvert Global Water Fund seeks to invest in a wide range of companies and other enterprises that demonstrate varying degrees of commitment and progress toward addressing key corporate responsibility and sustainability challenges.

Each underlying fund (other than Calvert Global Water Fund) has sustainable and socially responsible investment criteria that reflect specific types of companies in which the fund seeks to invest and seeks to avoid investing. Calvert Global Water Fund’s sustainable and socially responsible investment criteria reflect threshold responsibility standards used in determining whether a security qualifies as an investment for the fund, and specific types of companies in which the fund seeks to invest.

Investments for each underlying fund are first selected for financial soundness and then evaluated according to the fund’s sustainable and socially responsible investment criteria. Investments for each underlying fund must be consistent with the fund’s current investment criteria, including financial, sustainability and social responsibility factors, as well as threshold responsibility standards (for Calvert Global Water Fund only), the application of which is in the economic interest of the underlying fund and its shareholders.

Principal Risks

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Asset Allocation Risk. The Advisor’s selection of underlying funds and the allocation of Fund assets to those funds may cause the Fund to underperform. The Fund’s greater allocation to equity funds makes it more susceptible to risks associated with equity investments than fixed-income investments.

Management Risk. Individual investments of an underlying fund may not perform as expected, and the underlying fund’s portfolio management practices may not achieve the desired result.

Derivatives Risk. In general, a derivative is a financial contract whose value is based on the value of a financial asset (such as a stock, bond, or currency), a physical asset (such as gold), or a market index (such as the S&P 500 Index). Derivative instruments are subject to a number of risks, including the risk of changes in the market price of the underlying asset, credit risk with respect to the counterparty, and liquidity risk. The Fund’s use of certain derivatives may also have a leveraging effect, which may increase the volatility of the Fund and reduce its returns.

Exchange-Traded Fund (“ETF”) Risk. An ETF seeks to track the performance of an index by holding in its portfolio shares of all the companies, or a representative sample of the companies, that are components of a particular index. The risks of investment in ETFs typically reflect the risk of the types of securities in which the ETFs invest. In addition, when the Fund invests in an ETF, shareholders of the Fund bear their proportionate share of the ETF’s fees and expenses as well as their share of the Fund’s fees and expenses.

Equity Investments. The Fund shares the principal risks of equity securities held by the underlying funds, including the key risks below.

Stock Market Risk. The market prices of stocks held by the underlying funds may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Fixed-Income Investments. The Fund shares the principal risks of fixed-income securities held by the underlying funds, including the key risks below.

Bond Market Risk. The market prices of bonds held by the underlying funds may fall.

Interest Rate Risk. A change in interest rates may adversely affect the value of the securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.

Credit Risk. The credit quality of the securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.

Money Market Investments. The Fund shares the principal risks of money market securities held by the underlying funds, including the key risk below.

Money Market Risk. Yield will change in response to market interest rates; in general, as market rates go up, so will yield, and vice versa. Although the underlying fund tries to keep the value of its shares constant at $1.00 per share, changes in market rates could cause the value to decrease. Credit quality of the securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due. Credit risk, however, should be low for the underlying fund because it invests primarily in securities that are considered to be of high quality; the underlying fund also limits the amount it invests in any one issuer to try to lessen its exposure to credit risk.

Performance

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of a broad-based securities market index, a composite index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

The return for the Fund’s other Class of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Calendar Year Total Returns for Class A at NAV

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	6/30/09	16.87	%
Worst Quarter (of periods shown)	12/31/08	-21.79	%

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Average Annual Total Returns Retail Calvert Aggressive Allocation Fund		1 Year	5 Years	Since Inception	Inception Date
Class A		9.80%	(1.32%)	2.25%	Jun. 30, 2005
Class A Return after taxes on distributions		9.69%	(1.55%)	1.96%
Class A Return after taxes on distributions and sale of Fund shares		6.52%	(1.17%)	1.86%
Class C		12.79%	(1.67%)	1.60%	Jun. 30, 2005
Russell 3000 Index (reflects no deduction for fees, expenses or taxes)		16.42%	2.04%	4.87%
Aggressive Allocation Composite Index (reflects no deduction for fees, expenses or taxes)	[1]	16.17%	1.32%	4.93%
Lipper Multi-Cap Core Funds Avg. (reflects no deduction for taxes)		15.09%	0.98%	4.16%

[1] The contingent deferred sales charge reduces over time.

[1] The investment advisor has agreed to contractually limit direct ordinary operating expenses through January 31, 2014. This expense limitation does not limit the acquired fund fees and expenses paid indirectly by a shareholder. Direct ordinary operating expenses will not exceed 0.43% for Class A and 2.00% for Class C. Only the Board of Trustees of the Fund may terminate the Fund's expense limitation before the contractual period expires.

[1] The Fund also shows the Aggressive Allocation Composite Index (64% Russell 3000 Index; 26% Morgan Stanley Capital International Europe Australasia Far East Global Investable Market Index; 10% Barclays U.S. Credit Index) because it is more consistent with the Fund's portfolio construction process and represents a more accurate reflection of the Fund's anticipated risk and return patterns.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

CALVERT SOCIAL INVESTMENT FUND

Prospectus Date

rr_ProspectusDate

Jan. 31, 2013

Retail | Calvert Balanced Portfolio

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

CALVERT BALANCED PORTFOLIO
Class  (Ticker):   A  (CSIFX)   B  (CSLBX)   C  (CSGCX)

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to achieve a competitive total return through an actively managed portfolio of stocks, bonds, and money market instruments which offer income and capital growth opportunity and which satisfy the investment criteria, including financial, sustainability and social responsibility factors. This objective may be changed by the Fund's Board of Trustees without shareholder approval.

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 89 and “Reduced Sales Charges” on page 92 of this Prospectus, and under “Method of Distribution” on page 58 of the Fund’s Statement of Additional Information (“SAI”).

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as
a % of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 145% of its portfolio’s average value.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

145.00%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

The contingent deferred sales charge reduces over time.

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

50,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.  The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;

• your investment has a 5% return each year; and

• the Fund’s operating expenses remain the same.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund typically invests about 60% of its net assets in stocks and 40% in bonds or other fixed-income investments. Stock investments are primarily common stock in large-cap companies. Fixed-income investments are primarily a wide variety of investment grade debt securities, such as corporate debt securities, mortgage-backed securities (including commercial mortgage-backed securities and collateralized mortgage obligations ("CMOs")) and other asset-backed securities ("ABS"). The Fund invests in debt and mortgage-backed securities issued by government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”). The Fund may also invest in repurchase agreements.

An investment grade debt security is rated BBB- or higher by a nationally recognized statistical rating organization (“NRSRO”), or is an unrated bond determined by the Advisor to be of comparable credit quality. The Fund may also invest in unrated debt securities.

The Fund invests in a combination of stocks, bonds and money market instruments in an attempt to provide a complete investment portfolio in a single product. The Advisor monitors the Fund’s allocation and may rebalance or reallocate the Fund’s assets based on its view of economic and market factors and events. The equity portion of the Fund is primarily a large cap core U.S. domestic portfolio, although the Fund may also invest in foreign stocks and mid-cap stocks. The equity portion of the Fund seeks companies that have the potential to outperform the market through exceptional growth and/or valuation improvement. The fixed-income portion of the Fund reflects an active trading strategy, seeking total return.

The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund.

The Fund may also use futures contracts as a substitute for direct investment in a particular asset class, in order to facilitate the periodic rebalancing of the Fund’s portfolio to maintain its target asset allocation, to make tactical asset allocations and to assist in managing cash.

The Subadvisors select the equity investments, while the Advisor manages the fixed-income assets and determines the overall asset class mix for the Fund depending upon its view of market conditions and economic outlook.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result. There is a risk that the Advisor may allocate assets to an asset class that underperforms other asset classes.

Stock Market Risk. The market prices of stocks held by the Fund may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Large-Cap Company Risk. Large-cap companies may be unable to respond quickly to new competitive challenges such as changes in technology, and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Mid-Cap Company Risk. Prices of mid-cap stocks can be more volatile than those of larger, more established companies. Mid-cap companies are more likely to have more limited product lines, fewer capital resources and less depth of management than larger companies.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from differences between regulations that apply to U.S. and foreign issuers and markets, and the potential for foreign markets to be less liquid and more volatile than U.S. markets.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall.

Bond Market Risk. The market prices of bonds held by the Fund may fall.

Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.

Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.

Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.

Mortgage-Backed Securities Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by GSEs such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.

Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.

Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable quality. The Fund’s purchase of unrated securities depends on the Advisor’s analysis of credit risk without the assessment of an NRSRO.

Active Trading Strategy Risk. The fixed-income portion of the Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.

Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts.

Repurchase Agreement Risk. A repurchase agreement exposes the fixed-income portion of the Fund to the risk that the party that sells the security may default on its obligation to repurchase it. The Fund may lose money because it cannot sell the security at the agreed-upon time and price or the security loses value before it can be sold.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of a broad-based securities market index, a composite index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

The return for each of the Fund’s other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart shows how the performance of the Class A shares has varied from year to year.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.calvert.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Calendar Year Total Returns for Class A at NAV

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/09	11.47	%
Worst Quarter (of periods shown)	12/31/08	-18.24	%

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns
(as of 12/31/12) (with maximum sales
charge deducted)

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Retail | Calvert Balanced Portfolio | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.75%

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.70%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.23%

Other expenses

rr_OtherExpensesOverAssets

0.29%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.02%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.24%

1 Year

rr_ExpenseExampleYear01

595

3 Years

rr_ExpenseExampleYear03

850

5 Years

rr_ExpenseExampleYear05

1,124

10 Years

rr_ExpenseExampleYear10

1,904

2003

rr_AnnualReturn2003

17.49%

2004

rr_AnnualReturn2004

7.84%

2005

rr_AnnualReturn2005

5.18%

2006

rr_AnnualReturn2006

8.43%

2007

rr_AnnualReturn2007

3.23%

2008

rr_AnnualReturn2008

(28.98%)

2009

rr_AnnualReturn2009

23.93%

2010

rr_AnnualReturn2010

10.90%

2011

rr_AnnualReturn2011

3.28%

2012

rr_AnnualReturn2012

10.83%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter (of periods shown)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

11.47%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter (of periods shown)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(18.24%)

1 Year

rr_AverageAnnualReturnYear01

5.57%

5 Years

rr_AverageAnnualReturnYear05

1.25%

10 Years

rr_AverageAnnualReturnYear10

4.73%

Retail | Calvert Balanced Portfolio | Class B

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

5.00%

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.70%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.53%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.02%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.25%

1 Year

rr_ExpenseExampleYear01

728

3 Years

rr_ExpenseExampleYear03

1,103

5 Years

rr_ExpenseExampleYear05

1,405

10 Years

rr_ExpenseExampleYear10

2,330

1 Year

rr_ExpenseExampleNoRedemptionYear01

228

3 Years

rr_ExpenseExampleNoRedemptionYear03

703

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,205

10 Years

rr_ExpenseExampleNoRedemptionYear10

2,330

1 Year

rr_AverageAnnualReturnYear01

4.73%

5 Years

rr_AverageAnnualReturnYear05

1.02%

10 Years

rr_AverageAnnualReturnYear10

4.19%

Retail | Calvert Balanced Portfolio | Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

1.00%

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.70%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.35%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.02%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.07%

1 Year

rr_ExpenseExampleYear01

310

3 Years

rr_ExpenseExampleYear03

649

5 Years

rr_ExpenseExampleYear05

1,114

10 Years

rr_ExpenseExampleYear10

2,400

1 Year

rr_ExpenseExampleNoRedemptionYear01

210

3 Years

rr_ExpenseExampleNoRedemptionYear03

649

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,114

10 Years

rr_ExpenseExampleNoRedemptionYear10

2,400

1 Year

rr_AverageAnnualReturnYear01

8.91%

5 Years

rr_AverageAnnualReturnYear05

1.36%

10 Years

rr_AverageAnnualReturnYear10

4.28%

Retail | Calvert Balanced Portfolio | Return after taxes on distributions | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

5.45%

5 Years

rr_AverageAnnualReturnYear05

0.98%

10 Years

rr_AverageAnnualReturnYear10

4.32%

Retail | Calvert Balanced Portfolio | Return after taxes on distributions and sale of Fund shares | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

3.79%

5 Years

rr_AverageAnnualReturnYear05

0.95%

10 Years

rr_AverageAnnualReturnYear10

3.98%

Retail | Calvert Balanced Portfolio | Russell 1000 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

16.42%

5 Years

rr_AverageAnnualReturnYear05

1.92%

10 Years

rr_AverageAnnualReturnYear10

7.52%

Retail | Calvert Balanced Portfolio | Balanced Composite Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

13.60%

^[2]

5 Years

rr_AverageAnnualReturnYear05

4.21%

^[2]

10 Years

rr_AverageAnnualReturnYear10

7.01%

^[2]

Retail | Calvert Balanced Portfolio | Lipper Mixed-Asset Target Allocation Growth Funds Avg. (reflects no deduction for taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

12.63%

5 Years

rr_AverageAnnualReturnYear05

1.72%

10 Years

rr_AverageAnnualReturnYear10

6.48%

[1] The contingent deferred sales charge reduces over time.

[2] The Fund also shows the Balanced Composite Index (60% Russell 1000 Index; 40% Barclays U.S. Credit Index) because it is more consistent with the Fund's portfolio construction process and represents a more accurate reflection of the Fund's anticipated risk and return patterns.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

CALVERT SOCIAL INVESTMENT FUND

Prospectus Date

rr_ProspectusDate

Jan. 31, 2013

Institutional | Calvert Balanced Portfolio

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

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CALVERT BALANCED PORTFOLIO
Class   (Ticker):   I  (CBAIX)

Objective [Heading]

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INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

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The Fund seeks to achieve a competitive total return through an actively managed portfolio of stocks, bonds, and money market instruments which offer income and capital growth opportunity and which satisfy the investment criteria, including financial, sustainability and social responsibility factors. This objective may be changed by the Fund’s Board of Trustees without shareholder approval.

Expense [Heading]

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FEES AND EXPENSES OF THE FUND

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees Caption [Text]

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Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

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January 31, 2014

Portfolio Turnover [Heading]

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Portfolio Turnover

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 145% of its portfolio’s average value.

Portfolio Turnover, Rate

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145.00%

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $1,000,000 in the Fund for the time periods indicated;
• your investment has a 5% return each year;
• the Fund’s operating expenses remain the same; and
• any Calvert expense limitation is in effect for the period indicated in the fee table above.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Strategy [Heading]

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INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

Strategy Narrative [Text Block]

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The Fund typically invests about 60% of its net assets in stocks and 40% in bonds or other fixed-income investments. Stock investments are primarily common stock in large-cap companies. Fixed-income investments are primarily a wide variety of investment grade debt securities, such as corporate debt securities, mortgage-backed securities (including commercial mortgage-backed securities and collateralized mortgage obligations (“CMOs”)), and other asset-backed securities (“ABS”). The Fund invests in debt and mortgage-backed securities issued by government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”). The Fund may also invest in repurchase agreements.

An investment grade debt security is rated BBB- or higher by a nationally recognized statistical rating organization (“NRSRO”), or is an unrated bond determined by the Advisor to be of comparable credit quality. The Fund may also invest in unrated debt securities.

The Fund invests in a combination of stocks, bonds and money market instruments in an attempt to provide a complete investment portfolio in a single product. The Advisor monitors the Fund’s allocation and may rebalance or reallocate the Fund’s assets based on its view of economic and market factors and events. The equity portion of the Fund is primarily a large cap core U.S. domestic portfolio, although the Fund may also invest in foreign stocks and mid-cap stocks. The equity portion of the Fund seeks companies that have the potential to outperform the market through exceptional growth and/or valuation improvement. The fixed-income portion of the Fund reflects an active trading strategy, seeking total return.

The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund.

The Fund may also use futures contracts as a substitute for direct investment in a particular asset class, in order to facilitate the periodic rebalancing of the Fund’s portfolio to maintain its target asset allocation, to make tactical asset allocations and to assist in managing cash.

The Subadvisors select the equity investments, while the Advisor manages the fixed-income assets and determines the overall asset class mix for the Fund depending upon its view of market conditions and economic outlook.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Risk [Heading]

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Principal Risks

Risk Narrative [Text Block]

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You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result. There is a risk that the Advisor may allocate assets to an asset class that underperforms other asset classes.

Stock Market Risk. The market prices of stocks held by the Fund may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Large-Cap Company Risk. Large-cap companies may be unable to respond quickly to new competitive challenges such as changes in technology, and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Mid-Cap Company Risk. Prices of mid-cap stocks can be more volatile than those of larger, more established companies. Mid-cap companies are more likely to have more limited product lines, fewer capital resources and less depth of management than larger companies.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from differences between regulations that apply to U.S. and foreign issuers and markets, and the potential for foreign markets to be less liquid and more volatile than U.S. markets.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall.

Bond Market Risk. The market prices of bonds held by the Fund may fall.

Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.

Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.

Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.

Mortgage-Backed Securities Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by GSEs such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. Government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.

Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.

Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable quality. The Fund’s purchase of unrated securities depends on the Advisor’s analysis of credit risk without the assessment of an NRSRO.

Active Trading Strategy Risk. The fixed-income portion of the Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.

Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts.

Repurchase Agreement Risk. A repurchase agreement exposes the fixed-income portion of the Fund to the risk that the party that sells the security may default on its obligation to repurchase it. The Fund may lose money because it cannot sell the security at the agreed-upon time and price or the security loses value before it can be sold.

Risk Lose Money [Text]

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You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.

Risk Not Insured Depository Institution [Text]

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An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

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Performance

Performance Narrative [Text Block]

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The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class I shares has varied from year to year. The table compares the Fund’s performance over time with that of a broad-based securities market index, a composite index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

No shareholders held Class I shares for the period from June 30, 2003 through December 27, 2004. Performance results for Class I shares for this period reflect the performance of Class A shares at net asset value. Actual Class I share performance would have been higher than Class A share performance because Class I, unlike Class A, has no Rule 12b-1 fees.

Performance Information Illustrates Variability of Returns [Text]

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The bar chart shows how the performance of the Class I shares has varied from year to year.

Performance Availability Website Address [Text]

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www.calvert.com

Performance Past Does Not Indicate Future [Text]

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The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

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Calendar Year Total Returns

Bar Chart Closing [Text Block]

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	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/09	11.60	%
Worst Quarter (of periods shown)	12/31/08	-18.11	%

Performance Table Heading

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Average Annual Total Returns
(as of 12/31/12)

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.

Performance Table Explanation after Tax Higher

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The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Performance Table Narrative

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Institutional | Calvert Balanced Portfolio | Class I

Risk/Return:

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Redemption fee (as a % of amount redeemed or exchanged within 7 days of purchase)

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2.00%

Management fees

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0.55%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.28%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.02%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.85%

Fee Waiver or Reimbursement

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(0.11%)

^[1]

Net Expenses

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0.74%

1 Year

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7,558

3 Years

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26,025

5 Years

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46,057

10 Years

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103,880

2003

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17.81%

2004

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7.29%

2005

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6.24%

2006

rr_AnnualReturn2006

8.97%

2007

rr_AnnualReturn2007

3.69%

2008

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(28.62%)

2009

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24.63%

2010

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11.50%

2011

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3.80%

2012

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11.38%

Highest Quarterly Return, Label

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Best Quarter (of periods shown)

Highest Quarterly Return, Date

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Sep. 30, 2009

Highest Quarterly Return

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11.60%

Lowest Quarterly Return, Label

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Worst Quarter (of periods shown)

Lowest Quarterly Return, Date

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Dec. 31, 2008

Lowest Quarterly Return

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(18.11%)

1 Year

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11.38%

5 Years

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2.78%

10 Years

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5.69%

Institutional | Calvert Balanced Portfolio | Return after taxes on distributions | Class I

Risk/Return:

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1 Year

rr_AverageAnnualReturnYear01

11.18%

5 Years

rr_AverageAnnualReturnYear05

2.40%

10 Years

rr_AverageAnnualReturnYear10

5.21%

Institutional | Calvert Balanced Portfolio | Return after taxes on distributions and sale of Fund shares | Class I

Risk/Return:

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1 Year

rr_AverageAnnualReturnYear01

7.66%

5 Years

rr_AverageAnnualReturnYear05

2.22%

10 Years

rr_AverageAnnualReturnYear10

4.80%

Institutional | Calvert Balanced Portfolio | Russell 1000 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

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1 Year

rr_AverageAnnualReturnYear01

16.42%

5 Years

rr_AverageAnnualReturnYear05

1.92%

10 Years

rr_AverageAnnualReturnYear10

7.52%

Institutional | Calvert Balanced Portfolio | Balanced Composite Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

13.60%

^[2]

5 Years

rr_AverageAnnualReturnYear05

4.21%

^[2]

10 Years

rr_AverageAnnualReturnYear10

7.01%

^[2]

Institutional | Calvert Balanced Portfolio | Lipper Mixed-Asset Target Allocation Growth Funds Avg. (reflects no deduction for taxes)

Risk/Return:

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1 Year

rr_AverageAnnualReturnYear01

12.63%

5 Years

rr_AverageAnnualReturnYear05

1.72%

10 Years

rr_AverageAnnualReturnYear10

6.48%

[1] The investment advisor has agreed to contractually limit direct net annual fund operating expenses to 0.72% through January 31, 2014. This expense limitation does not limit the acquired fund fees and expenses paid indirectly by a shareholder. Only the Board of Trustees of the Fund may terminate the Fund's expense limitation before the contractual period expires.

[2] The Fund also shows the Balanced Composite Index (60% Russell 1000 Index; 40% Barclays U.S. Credit Index) because it is more consistent with the Fund's portfolio construction process and represents a more accurate reflection of the Fund's anticipated risk and return patterns.

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Retail | Calvert Balanced Portfolio

CALVERT BALANCED PORTFOLIO
Class  (Ticker):   A  (CSIFX)   B  (CSLBX)   C  (CSGCX)

INVESTMENT OBJECTIVE

The Fund seeks to achieve a competitive total return through an actively managed portfolio of stocks, bonds, and money market instruments which offer income and capital growth opportunity and which satisfy the investment criteria, including financial, sustainability and social responsibility factors. This objective may be changed by the Fund's Board of Trustees without shareholder approval.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 89 and “Reduced Sales Charges” on page 92 of this Prospectus, and under “Method of Distribution” on page 58 of the Fund’s Statement of Additional Information (“SAI”).

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Retail Calvert Balanced Portfolio		Class A	Class B	Class C
Maximum sales charge (load) on purchases (as a % of offering price)		4.75%	none	none
Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)	[1]	none	5.00%	1.00%
Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)		2.00%	2.00%	2.00%

Annual Fund Operating Expenses (expenses that you pay each year as
a % of the value of your investment)

Annual Fund Operating Expenses Retail Calvert Balanced Portfolio	Class A	Class B	Class C
Management fees	0.70%	0.70%	0.70%
Distribution and service (12b-1) fees	0.23%	1.00%	1.00%
Other expenses	0.29%	0.53%	0.35%
Acquired fund fees and expenses	0.02%	0.02%	0.02%
Total annual fund operating expenses	1.24%	2.25%	2.07%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.  The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;

• your investment has a 5% return each year; and

• the Fund’s operating expenses remain the same.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Expense Example Retail Calvert Balanced Portfolio (USD $)	1 Year	3 Years	5 Years	10 Years
Class A	595	850	1,124	1,904
Class B	728	1,103	1,405	2,330
Class C	310	649	1,114	2,400

Expense Example, No Redemption Retail Calvert Balanced Portfolio (USD $)	1 Year	3 Years	5 Years	10 Years
Class B	228	703	1,205	2,330
Class C	210	649	1,114	2,400

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 145% of its portfolio’s average value.

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

The Fund typically invests about 60% of its net assets in stocks and 40% in bonds or other fixed-income investments. Stock investments are primarily common stock in large-cap companies. Fixed-income investments are primarily a wide variety of investment grade debt securities, such as corporate debt securities, mortgage-backed securities (including commercial mortgage-backed securities and collateralized mortgage obligations ("CMOs")) and other asset-backed securities ("ABS"). The Fund invests in debt and mortgage-backed securities issued by government-sponsored enterprises (“GSEs”) such as the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”). The Fund may also invest in repurchase agreements.

An investment grade debt security is rated BBB- or higher by a nationally recognized statistical rating organization (“NRSRO”), or is an unrated bond determined by the Advisor to be of comparable credit quality. The Fund may also invest in unrated debt securities.

The Fund invests in a combination of stocks, bonds and money market instruments in an attempt to provide a complete investment portfolio in a single product. The Advisor monitors the Fund’s allocation and may rebalance or reallocate the Fund’s assets based on its view of economic and market factors and events. The equity portion of the Fund is primarily a large cap core U.S. domestic portfolio, although the Fund may also invest in foreign stocks and mid-cap stocks. The equity portion of the Fund seeks companies that have the potential to outperform the market through exceptional growth and/or valuation improvement. The fixed-income portion of the Fund reflects an active trading strategy, seeking total return.

The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund.

The Fund may also use futures contracts as a substitute for direct investment in a particular asset class, in order to facilitate the periodic rebalancing of the Fund’s portfolio to maintain its target asset allocation, to make tactical asset allocations and to assist in managing cash.

The Subadvisors select the equity investments, while the Advisor manages the fixed-income assets and determines the overall asset class mix for the Fund depending upon its view of market conditions and economic outlook.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Principal Risks

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result. There is a risk that the Advisor may allocate assets to an asset class that underperforms other asset classes.

Stock Market Risk. The market prices of stocks held by the Fund may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Large-Cap Company Risk. Large-cap companies may be unable to respond quickly to new competitive challenges such as changes in technology, and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Mid-Cap Company Risk. Prices of mid-cap stocks can be more volatile than those of larger, more established companies. Mid-cap companies are more likely to have more limited product lines, fewer capital resources and less depth of management than larger companies.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from differences between regulations that apply to U.S. and foreign issuers and markets, and the potential for foreign markets to be less liquid and more volatile than U.S. markets.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall.

Bond Market Risk. The market prices of bonds held by the Fund may fall.

Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.

Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.

Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.

Mortgage-Backed Securities Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by GSEs such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.

Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.

Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable quality. The Fund’s purchase of unrated securities depends on the Advisor’s analysis of credit risk without the assessment of an NRSRO.

Active Trading Strategy Risk. The fixed-income portion of the Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.

Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts.

Repurchase Agreement Risk. A repurchase agreement exposes the fixed-income portion of the Fund to the risk that the party that sells the security may default on its obligation to repurchase it. The Fund may lose money because it cannot sell the security at the agreed-upon time and price or the security loses value before it can be sold.

Performance

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of a broad-based securities market index, a composite index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

The return for each of the Fund’s other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Calendar Year Total Returns for Class A at NAV

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/09	11.47	%
Worst Quarter (of periods shown)	12/31/08	-18.24	%

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Average Annual Total Returns
(as of 12/31/12) (with maximum sales
charge deducted)

Average Annual Total Returns Retail Calvert Balanced Portfolio		1 Year	5 Years	10 Years
Class A		5.57%	1.25%	4.73%
Class A Return after taxes on distributions		5.45%	0.98%	4.32%
Class A Return after taxes on distributions and sale of Fund shares		3.79%	0.95%	3.98%
Class B		4.73%	1.02%	4.19%
Class C		8.91%	1.36%	4.28%
Russell 1000 Index (reflects no deduction for fees, expenses or taxes)		16.42%	1.92%	7.52%
Balanced Composite Index (reflects no deduction for fees, expenses or taxes)	[1]	13.60%	4.21%	7.01%
Lipper Mixed-Asset Target Allocation Growth Funds Avg. (reflects no deduction for taxes)		12.63%	1.72%	6.48%

[1] The contingent deferred sales charge reduces over time.

[1] The Fund also shows the Balanced Composite Index (60% Russell 1000 Index; 40% Barclays U.S. Credit Index) because it is more consistent with the Fund's portfolio construction process and represents a more accurate reflection of the Fund's anticipated risk and return patterns.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

CALVERT SOCIAL INVESTMENT FUND

Prospectus Date

rr_ProspectusDate

Jan. 31, 2013

Retail | Calvert Equity Portfolio

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

CALVERT EQUITY PORTFOLIO
Class  (Ticker):   A  (CSIEX)   B  (CSEBX)   C  (CSECX)   Y  (CIEYX)

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks growth of capital through investment in stocks believed to offer opportunities for potential capital appreciation and which meet the Fund’s investment criteria, including financial, sustainability and social responsibility factors. This objective may be changed by the Fund's Board of Trustees without shareholder approval.

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 89 and “Reduced Sales Charges” on page 92 of this Prospectus, and under “Method of Distribution” on page 58 of the Fund’s Statement of Additional Information (“SAI”).

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a % of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 36% of its portfolio’s average value.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

36.00%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

The contingent deferred sales charge reduces over time.

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

50,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;
• your investment has a 5% return each year; and
• the Fund’s operating expenses remain the same.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund normally invests at least 80% of its net assets, including borrowings for investment purposes, in equity securities (common stock). The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy. The Fund invests primarily in common stocks of U.S. large-cap companies. The Fund defines large-cap companies as those whose market capitalization falls within the range of the Standard & Poor’s (“S&P”) 500 Index. As of December 31, 2012, the market capitalization of the S&P 500 Index companies ranged from $1.63 billion to $500 billion with a weighted median level of $56.8 billion and a weighted average level of $106.1 billion. The Fund normally seeks to have a weighted average market capitalization of at least $20 billion.

The Fund may also invest in mid-cap stocks and may invest up to 25% of its net assets in foreign stocks.

The Subadvisor looks for established companies with a history of steady earnings growth. The Subadvisor selects companies based on its opinion that the company has the ability to sustain growth through high profitability and that the stock is favorably priced with respect to those growth expectations.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.

Stock Market Risk. The market prices of stocks held by the Fund may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Large-Cap Company Risk. Large-cap companies may be unable to respond quickly to new competitive challenges such as changes in technology, and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Mid-Cap Company Risk. Prices of mid-cap stocks can be more volatile than those of larger, more established companies. Mid-cap companies are more likely to have more limited product lines, fewer capital resources and less depth of management than larger companies.

Growth Company Risk. Prices of growth company securities may fall more than the overall equity markets due to changing economic, political or market conditions or disappointing growth company earnings results. Growth stocks also generally lack the dividends of some value stocks that can cushion stock prices in a falling market.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from differences between regulations that apply to U.S. and foreign issuers and markets, and the potential for foreign markets to be less liquid and more volatile than U.S. markets.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of an index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

Performance results for Class Y shares prior to 10/31/08 (the Class Y shares’ inception date) reflect the performance of Class A shares at net asset value. Actual Class Y share performance would have been higher than Class A share performance because Class Y, unlike Class A, has no Rule 12b-1 fees.

The return for each of the Fund’s other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart shows how the performance of the Class A shares has varied from year to year.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.calvert.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Calendar Year Total Returns for Class A at NAV

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	6/30/09	17.97	%
Worst Quarter (of periods shown)	12/31/08	-24.39	%

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns
(as of 12/31/12) (with maximum sales
charge deducted, if any)

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Retail | Calvert Equity Portfolio | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.75%

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.70%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.26%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.22%

1 Year

rr_ExpenseExampleYear01

593

3 Years

rr_ExpenseExampleYear03

844

5 Years

rr_ExpenseExampleYear05

1,113

10 Years

rr_ExpenseExampleYear10

1,882

2003

rr_AnnualReturn2003

22.31%

2004

rr_AnnualReturn2004

6.69%

2005

rr_AnnualReturn2005

4.16%

2006

rr_AnnualReturn2006

10.16%

2007

rr_AnnualReturn2007

9.94%

2008

rr_AnnualReturn2008

(35.53%)

2009

rr_AnnualReturn2009

33.41%

2010

rr_AnnualReturn2010

17.23%

2011

rr_AnnualReturn2011

(2.23%)

2012

rr_AnnualReturn2012

15.52%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter (of periods shown)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

17.97%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter (of periods shown)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(24.39%)

1 Year

rr_AverageAnnualReturnYear01

10.04%

5 Years

rr_AverageAnnualReturnYear05

1.64%

10 Years

rr_AverageAnnualReturnYear10

5.97%

Retail | Calvert Equity Portfolio | Class B

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

5.00%

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.70%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.39%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.10%

1 Year

rr_ExpenseExampleYear01

713

3 Years

rr_ExpenseExampleYear03

1,058

5 Years

rr_ExpenseExampleYear05

1,329

10 Years

rr_ExpenseExampleYear10

2,206

1 Year

rr_ExpenseExampleNoRedemptionYear01

213

3 Years

rr_ExpenseExampleNoRedemptionYear03

658

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,129

10 Years

rr_ExpenseExampleNoRedemptionYear10

2,206

1 Year

rr_AverageAnnualReturnYear01

9.49%

5 Years

rr_AverageAnnualReturnYear05

1.53%

10 Years

rr_AverageAnnualReturnYear10

5.57%

Retail | Calvert Equity Portfolio | Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

1.00%

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.70%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.24%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.95%

1 Year

rr_ExpenseExampleYear01

298

3 Years

rr_ExpenseExampleYear03

612

5 Years

rr_ExpenseExampleYear05

1,052

10 Years

rr_ExpenseExampleYear10

2,275

1 Year

rr_ExpenseExampleNoRedemptionYear01

198

3 Years

rr_ExpenseExampleNoRedemptionYear03

612

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,052

10 Years

rr_ExpenseExampleNoRedemptionYear10

2,275

1 Year

rr_AverageAnnualReturnYear01

13.69%

5 Years

rr_AverageAnnualReturnYear05

1.85%

10 Years

rr_AverageAnnualReturnYear10

5.67%

Retail | Calvert Equity Portfolio | Class Y

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.70%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.12%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.83%

1 Year

rr_ExpenseExampleYear01

85

3 Years

rr_ExpenseExampleYear03

265

5 Years

rr_ExpenseExampleYear05

460

10 Years

rr_ExpenseExampleYear10

1,025

1 Year

rr_AverageAnnualReturnYear01

15.96%

5 Years

rr_AverageAnnualReturnYear05

2.93%

10 Years

rr_AverageAnnualReturnYear10

6.64%

Retail | Calvert Equity Portfolio | Return after taxes on distributions | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

10.01%

5 Years

rr_AverageAnnualReturnYear05

1.24%

10 Years

rr_AverageAnnualReturnYear10

5.57%

Retail | Calvert Equity Portfolio | Return after taxes on distributions and sale of Fund shares | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

6.56%

5 Years

rr_AverageAnnualReturnYear05

1.30%

10 Years

rr_AverageAnnualReturnYear10

5.17%

Retail | Calvert Equity Portfolio | S&P 500 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

16.00%

5 Years

rr_AverageAnnualReturnYear05

1.66%

10 Years

rr_AverageAnnualReturnYear10

7.10%

Retail | Calvert Equity Portfolio | Lipper Large-Cap Growth Funds Avg. (reflects no deduction for taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

15.26%

5 Years

rr_AverageAnnualReturnYear05

1.19%

10 Years

rr_AverageAnnualReturnYear10

6.67%

[1] The contingent deferred sales charge reduces over time.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	CALVERT SOCIAL INVESTMENT FUND
Prospectus Date	rr_ProspectusDate	Jan. 31, 2013
Document Creation Date	dei_DocumentCreationDate	Jan. 30, 2013

XML

Document and Entity Information	12 Months Ended
	Jan. 31, 2013
Risk/Return:
Document Type	485BPOS
Document Period End Date	Sep. 30, 2012
Registrant Name	CALVERT SOCIAL INVESTMENT FUND
Central Index Key	0000356682
Amendment Flag	false
Document Creation Date	Jan. 30, 2013
Document Effective Date	Jan. 31, 2013
Prospectus Date	Jan. 31, 2013

XML

Retail | Calvert Large Cap Core Portfolio

CALVERT LARGE CAP CORE PORTFOLIO*
Class  (Ticker):   A  (CMIFX)   B  (CDXBX)   C  (CMICX)

*Formerly named Calvert Enhanced Equity Portfolio.

INVESTMENT OBJECTIVE

The Fund seeks to provide a total return which exceeds the total return of the Russell 1000 Index over a market cycle through investment in securities that meet the Fund’s investment criteria, including financial, sustainability and social responsibility factors.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 89 and “Reduced Sales Charges” on page 92 of this Prospectus, and under “Method of Distribution” on page 58 of the Fund’s Statement of Additional Information (“SAI”).

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Retail Calvert Large Cap Core Portfolio		Class A	Class B	Class C
Maximum sales charge (load) on purchases (as a % of offering price)		4.75%	none	none
Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)	[1]	none	5.00%	1.00%
Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)		2.00%	2.00%	2.00%

Annual Fund Operating Expenses (expenses that you pay each year as
a % of the value of your investment)

Annual Fund Operating Expenses Retail Calvert Large Cap Core Portfolio	Class A	Class B	Class C
Management fees	0.75%	0.75%	0.75%
Distribution and service (12b-1) fees	0.25%	1.00%	1.00%
Other expenses	0.40%	1.20%	0.51%
Total annual fund operating expenses	1.40%	2.95%	2.26%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;
• your investment has a 5% return each year; and
• the Fund’s operating expenses remain the same.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Expense Example Retail Calvert Large Cap Core Portfolio (USD $)	1 Year	3 Years	5 Years	10 Years
Class A	611	897	1,204	2,075
Class B	798	1,313	1,752	2,904
Class C	329	706	1,210	2,595

Expense Example, No Redemption Retail Calvert Large Cap Core Portfolio (USD $)	1 Year	3 Years	5 Years	10 Years
Class B	298	913	1,552	2,904
Class C	229	706	1,210	2,595

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 48% of its portfolio’s average value.

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

The Fund employs an active investment strategy and invests primarily in the common stocks of U.S. large-cap companies that meet the Fund’s investment criteria, including financial, sustainability and social responsibility investment factors, using quantitative, fundamental, and macro-economic insights that are designed to identify stocks with the greatest potential to outperform the market. Insights from this stock selection process are enhanced by the Advisor’s fundamental investment research, which seeks to add value by integrating traditional fundamental investment analysis with the Advisor’s proprietary views on critical environmental, sustainability and governance issues. The portfolio construction process seeks to maximize the benefit of these insights while controlling the Fund’s risk profile relative to its benchmark, the Russell 1000 Index, and minimizing transaction costs. The Fund may sell a security when it no longer appears attractive under this process or if it contributes disproportionately to portfolio risk.

The Fund will normally invest at least 80% of its net assets, including borrowings for investment purposes, in the equity securities (common stock) of large capitalization companies.

*Formerly named Calvert Enhanced Equity Portfolio.

The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy.

The Fund defines large-cap companies as those within the range of market capitalizations of the Russell 1000 Index. The Russell 1000 Index measures the performance of the 1,000 largest U.S. companies based on the float-adjusted market capitalization of the index constituents. The Russell 1000 Index is adjusted, or reconstituted, annually. As of December 31, 2012, the market capitalization of the Russell 1000 Index ranged from $317 million to $500 billion with a weighted median level of $42.9 billion and a weighted average level of $94.3 billion. Although primarily investing in large-cap U.S. companies, the Fund may also invest in mid-cap and small-cap companies. The Fund may not invest more than 25% of its net assets in foreign securities. The Advisor rebalances the Fund as market conditions warrant while attempting to minimize transaction costs and adhere to its long-term investment objective.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Principal Risks

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.

Stock Market Risk. The market prices of stocks held by the Fund may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors' perception of a company's well-being.

Large-Cap Company Risk. Large-cap companies may be unable to respond quickly to new competitive challenges such as changes in technology, and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Small-Cap and Mid-Cap Company Risk. Prices of small-cap and mid-cap stocks can be more volatile than those of larger, more established companies. Small-cap and mid-cap companies are more likely to have more limited product lines, fewer capital resources and less depth of management than larger companies.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from differences between regulations that apply to U.S. and foreign issuers and markets, and the potential for foreign markets to be less liquid and more volatile than U.S. markets.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall.

Performance

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of an index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

The return for each of the Fund’s other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Calendar Year Total Returns for Class A at NAV

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/09	17.31	%
Worst Quarter (of periods shown)	12/31/08	-23.84	%

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Average Annual Total Returns
(as of 12/31/12) (with maximum
sales charge deducted)

Average Annual Total Returns Retail Calvert Large Cap Core Portfolio	1 Year	5 Years	10 Years
Class A	8.94%	0.05%	4.66%
Class A Return after taxes on distributions	8.80%	(0.09%)	4.37%
Class A Return after taxes on distributions and sale of Fund shares	6.00%	0.01%	4.04%
Class B	7.85%	(0.47%)	4.01%
Class C	12.41%	0.12%	4.24%
Russell 1000 Index (reflects no deduction for fees, expenses or taxes)	16.42%	1.92%	7.52%
Lipper Large-Cap Core Funds Avg. (reflects no deduction for taxes)	14.95%	0.68%	6.51%

[1] The contingent deferred sales charge reduces over time.

XML

Institutional | Calvert Large Cap Core Portfolio

CALVERT LARGE CAP CORE PORTFOLIO*
Class  (Ticker):   I  (CMIIX)

*Formerly named Calvert Enhanced Equity Portfolio.

INVESTMENT OBJECTIVE

The Fund seeks to provide a total return which exceeds the total return of the Russell 1000 Index over a market cycle through investment in securities that meet the Fund’s investment criteria, including financial, sustainability and social responsibility factors.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Institutional Calvert Large Cap Core Portfolio Class I
Redemption fee (as a % of amount redeemed or exchanged within 7 days of purchase)	2.00%

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Annual Fund Operating Expenses		Institutional Calvert Large Cap Core Portfolio Class I
Management fees		0.70%
Distribution and service (12b-1) fees		none
Other expenses		0.17%
Total annual fund operating expenses		0.87%
Less fee waiver and/or expense reimbursement	[1]	(0.06%)
Net Expenses		0.81%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $1,000,000 in the Fund for the time periods indicated;
• your investment has a 5% return each year;
• the Fund’s operating expenses remain the same; and
• any Calvert expense limitation is in effect for the period indicated in the fee table above.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Institutional Calvert Large Cap Core Portfolio Class I	8,270	27,155	47,633	106,702

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 48% of its portfolio’s average value.

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

The Fund employs an active investment strategy and invests primarily in the common stocks of U.S. large-cap companies that meet the Fund’s investment criteria, including financial, sustainability and social responsibility investment factors, using quantitative, fundamental, and macro-economic insights that are designed to identify stocks with the greatest potential to outperform the market. Insights from this stock selection process are enhanced by the Advisor’s fundamental investment research, which seeks to add value by integrating traditional fundamental investment analysis with the Advisor’s proprietary views on critical environmental, sustainability and governance issues. The portfolio construction process seeks to maximize the benefit of these insights while controlling the Fund’s risk profile relative to its benchmark, the Russell 1000 Index, and minimizing transaction costs. The Fund may sell a security when it no longer appears attractive under this process or if it contributes disproportionately to portfolio risk.

The Fund will normally invest at least 80% of its net assets, including borrowings for investment purposes, in the equity securities (common stock) of large capitalization companies. The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy.

The Fund defines large-cap companies as those within the range of market capitalizations of the Russell 1000 Index. The Russell 1000 Index measures the performance of the 1,000 largest U.S. companies based on the float-adjusted market capitalization of the index constituents. The Russell 1000 Index is adjusted, or reconstituted, annually. As of December 31, 2012, the market capitalization of the Russell 1000 Index ranged from $317 million to $500 billion with a weighted median level of $42.9 billion and a weighted average level of $94.3 billion. Although primarily investing in large-cap U.S. companies, the Fund may also invest in mid-cap and small-cap companies. The Fund may not invest more than 25% of its net assets in foreign securities. The Advisor rebalances the Fund as market conditions warrant while attempting to minimize transaction costs and adhere to its long-term investment objective.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Principal Risks

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.

Stock Market Risk. The market prices of stocks held by the Fund may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition and on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Large-Cap Company Risk. Large-cap companies may be unable to respond quickly to new competitive challenges such as changes in technology, and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Small-Cap and Mid-Cap Company Risk. Prices of small-cap and mid-cap stocks can be more volatile than those of larger, more established companies. Small-cap and mid-cap companies are more likely to have more limited product lines, fewer capital resources and less depth of management than larger companies.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from differences between regulations that apply to U.S. and foreign issuers and markets, and the potential for foreign markets to be less liquid and more volatile than U.S. markets.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall.

Performance

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class I shares has varied from year to year. The table compares the Fund’s performance over time with that of an index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

No shareholders held Class I shares for the period from January 18, 2002 through April 29, 2005. Performance results for Class I shares for this period reflect the performance of Class A shares at net asset value. Actual Class I share performance would have been higher than Class A share performance because Class I, unlike Class A, has no Rule 12b-1 fees.

Calendar Year Total Returns

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/09	17.40	%
Worst Quarter (of periods shown)	12/31/08	-23.72	%

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Average Annual Total Returns
(as of 12/31/12)

Average Annual Total Returns Institutional Calvert Large Cap Core Portfolio	1 Year	5 Years	10 Years
Class I	15.01%	1.60%	5.57%
Class I Return after taxes on distributions	14.80%	1.40%	5.24%
Class I Return after taxes on distributions and sale of Fund shares	10.03%	1.33%	4.85%
Russell 1000 Index (reflects no deduction for fees, expenses or taxes)	16.42%	1.92%	7.52%
Lipper Large-Cap Core Funds Avg. (reflects no deduction for taxes)	14.95%	0.68%	6.51%

[1] The investment advisor has agreed to contractually limit direct net annual fund operating expenses to 0.81% through January 31, 2014. Only the Board of Trustees of the Fund may terminate the Fund's expense limitation before the contractual period expires.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

CALVERT SOCIAL INVESTMENT FUND

Prospectus Date

rr_ProspectusDate

Jan. 31, 2013

Calvert Money Market Portfolio

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

CALVERT MONEY MARKET PORTFOLIO
Class  (Ticker):   O  (CSIXX)

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide the highest level of current income, consistent with liquidity, safety and security of capital, through investment in money market instruments meeting the Fund’s investment criteria, including financial, sustainability and social responsibility factors. This objective may be changed by the Fund’s Board of Trustees without shareholder approval.

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated;
• your investment has a 5% return each year; and
• the Fund’s operating expenses remain the same.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund invests in high quality money market instruments, such as commercial paper, variable rate demand notes, corporate, agency and taxable municipal obligations, and repurchase agreements. All investments must comply with the SEC’s money market fund requirements per Rule 2a-7 of the Investment Company Act of 1940.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

Income Risk. The income level of the Fund will fluctuate with changing market conditions and interest rate levels. The income the Fund receives may fall as a result of a decline in interest rates.

Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall.

Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due. Credit risk, however, should be low for the Fund because it invests primarily in securities that are considered to be of high quality. The Fund also limits the amount it invests in any one issuer to try to lessen its exposure to credit risk.

Management Risk. The individual bonds in the Fund may not perform as expected, due to credit, political or other risks and/or the Fund’s portfolio management practices may not achieve the desired result.

Repurchase Agreement Risk. A repurchase agreement exposes the Fund to the risk that the party that sells the security may default on its obligation to repurchase it. The Fund may lose money because it cannot sell the security at the agreed-upon time and price or the security loses value before it can be sold.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.

Risk Money Market Fund [Text]

rr_RiskMoneyMarketFund

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class O shares has varied from year to year. The table compares the Fund’s performance over time with an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart shows how the performance of the Class O shares has varied from year to year.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.calvert.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Calendar Year Total Returns

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/07	1.15	%
Worst Quarter (of periods shown)	3/31/10	0.00	%

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns
(as of 12-31-11)

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

For current yield information, call 800-368-2745, or visit Calvert’s website at www.calvert.com.

Money Market Seven Day Yield Phone

rr_MoneyMarketSevenDayYieldPhone

800-368-2745

Calvert Money Market Portfolio | Class O

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.50%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.34%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.84%

1 Year

rr_ExpenseExampleYear01

86

3 Years

rr_ExpenseExampleYear03

268

5 Years

rr_ExpenseExampleYear05

466

10 Years

rr_ExpenseExampleYear10

1,037

2003

rr_AnnualReturn2003

0.49%

2004

rr_AnnualReturn2004

0.64%

2005

rr_AnnualReturn2005

2.47%

2006

rr_AnnualReturn2006

4.27%

2007

rr_AnnualReturn2007

4.55%

2008

rr_AnnualReturn2008

2.55%

2009

rr_AnnualReturn2009

0.43%

2010

rr_AnnualReturn2010

0.01%

2011

rr_AnnualReturn2011

0.01%

2012

rr_AnnualReturn2012

0.03%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter (of periods shown)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2007

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

1.15%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter (of periods shown)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

0.00%

1 Year

rr_AverageAnnualReturnYear01

0.03%

5 Years

rr_AverageAnnualReturnYear05

0.60%

10 Years

rr_AverageAnnualReturnYear10

1.53%

Calvert Money Market Portfolio | Lipper Money Market Funds Avg.

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

0.02%

5 Years

rr_AverageAnnualReturnYear05

0.47%

10 Years

rr_AverageAnnualReturnYear10

1.45%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

CALVERT SOCIAL INVESTMENT FUND

Prospectus Date

rr_ProspectusDate

Jan. 31, 2013

Institutional | Calvert Equity Portfolio

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

CALVERT EQUITY PORTFOLIO
Class  (Ticker):   I  (CEYIX)

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks growth of capital through investment in stocks believed to offer opportunities for potential capital appreciation and which meet the Fund’s investment criteria, including financial, sustainability and social responsibility factors. This objective may be changed by the Fund’s Board of Trustees without shareholder approval.

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 36% of its portfolio’s average value.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

36.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $1,000,000 in the Fund for the time periods indicated;
• your investment has a 5% return each year; and
• the Fund’s operating expenses remain the same.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund normally invests at least 80% of its net assets, including borrowings for investment purposes, in equity securities (common stock). The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy. The Fund invests primarily in common stocks of U.S. large-cap companies. The Fund defines large-cap companies as those whose market capitalization falls within the range of the Standard & Poor’s (“S&P”) 500 Index. As of December 31, 2012, the market capitalization of the S&P 500 Index companies ranged from $1.63 billion to $500 billion with a weighted median level of $56.8 billion and a weighted average level of $106.1 billion.

The Fund normally seeks to have a weighted average market capitalization of at least $20 billion.

The Fund may also invest in mid-cap stocks and may invest up to 25% of its net assets in foreign stocks.

The Subadvisor looks for established companies with a history of steady earnings growth. The Subadvisor selects companies based on its opinion that the company has the ability to sustain growth through high profitability and that the stock is favorably priced with respect to those growth expectations.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.

Stock Market Risk. The market prices of stocks held by the Fund may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Large-Cap Company Risk. Large-cap companies may be unable to respond quickly to new competitive challenges such as changes in technology, and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Mid-Cap Company Risk. Prices of mid-cap stocks can be more volatile than those of larger, more established companies. Mid-cap companies are more likely to have more limited product lines, fewer capital resources and less depth of management than larger companies.

Growth Company Risk. Prices of growth company securities may fall more than the overall equity markets due to changing economic, political or market conditions or disappointing growth company earnings results. Growth stocks also generally lack the dividends of some value stocks that can cushion stock prices in a falling market.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from differences between regulations that apply to U.S. and foreign issuers and markets, and the potential for foreign markets to be less liquid and more volatile than U.S. markets.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class I shares has varied from year to year. The table compares the Fund’s performance over time with that of an index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart shows how the performance of the Class I shares has varied from year to year.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

visit www.calvert.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Calendar Year Total Returns

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	6/30/09	18.18	%
Worst Quarter (of periods shown)	12/31/08	-24.28	%

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns
(as of 12/31/12)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Institutional | Calvert Equity Portfolio | Class I

Risk/Return:

rr_RiskReturnAbstract

Redemption fee (as a % of amount redeemed or exchanged within 7 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.60%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.07%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.68%

1 Year

rr_ExpenseExampleYear01

6,947

3 Years

rr_ExpenseExampleYear03

21,754

5 Years

rr_ExpenseExampleYear05

37,868

10 Years

rr_ExpenseExampleYear10

84,653

2003

rr_AnnualReturn2003

23.00%

2004

rr_AnnualReturn2004

7.33%

2005

rr_AnnualReturn2005

4.74%

2006

rr_AnnualReturn2006

10.77%

2007

rr_AnnualReturn2007

10.53%

2008

rr_AnnualReturn2008

(35.19%)

2009

rr_AnnualReturn2009

34.21%

2010

rr_AnnualReturn2010

17.86%

2011

rr_AnnualReturn2011

(1.70%)

2012

rr_AnnualReturn2012

16.14%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter (of periods shown)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

18.18%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter (of periods shown)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(24.28%)

1 Year

rr_AverageAnnualReturnYear01

16.14%

5 Years

rr_AverageAnnualReturnYear05

3.20%

10 Years

rr_AverageAnnualReturnYear10

7.08%

Institutional | Calvert Equity Portfolio | Return after taxes on distributions | Class I

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

16.10%

5 Years

rr_AverageAnnualReturnYear05

2.80%

10 Years

rr_AverageAnnualReturnYear10

6.69%

Institutional | Calvert Equity Portfolio | Return after taxes on distributions and sale of Fund shares | Class I

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

10.55%

5 Years

rr_AverageAnnualReturnYear05

2.64%

10 Years

rr_AverageAnnualReturnYear10

6.17%

Institutional | Calvert Equity Portfolio | S&P 500 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

16.00%

5 Years

rr_AverageAnnualReturnYear05

1.66%

10 Years

rr_AverageAnnualReturnYear10

7.10%

Institutional | Calvert Equity Portfolio | Lipper Large-Cap Growth Funds Avg. (reflects no deduction for taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

15.26%

5 Years

rr_AverageAnnualReturnYear05

1.19%

10 Years

rr_AverageAnnualReturnYear10

6.67%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

CALVERT SOCIAL INVESTMENT FUND

Prospectus Date

rr_ProspectusDate

Jan. 31, 2013

Institutional | Calvert Bond Portfolio

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

CALVERT BOND PORTFOLIO
Class (Ticker):    I (CBDIX)

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide as high a level of current income as is consistent with prudent investment risk and preservation of capital through investment in bonds and other debt securities meeting the Fund’s investment criteria, including financial, sustainability and social responsibility factors. This objective may be changed by the Fund's Board of Trustees without shareholder approval.

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 228% of its portfolio’s average value.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

228.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $1,000,000 in the Fund for the time periods indicated;
• your investment has a 5% return each year; and
• the Fund’s operating expenses remain the same.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund uses an active strategy, seeking relative value to earn incremental income. Under normal circumstances, the Fund invests at least 80% of its net assets (including borrowings for investment purposes) in bonds. Bonds include debt securities of any maturity. The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy. At least 80% of the Fund’s net assets will be invested in investment grade debt securities. A debt security is investment grade when assigned a credit quality rating of BBB- or higher by Standard & Poor’s Ratings Services ("Standard & Poor's") or an equivalent rating by another nationally recognized statistical rating organization (‘‘NRSRO”), including Moody’s Investors Service or Fitch Ratings, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.

The Fund invests principally in bonds issued by U.S. corporations, the U.S. Government or its agencies, and U.S. government-sponsored enterprises (e.g., the Federal National Mortgage Association (“FNMA”) and the Federal Home Loan Mortgage Corporation (“FHLMC”)). The Fund also may invest in trust preferred securities, taxable municipal securities, asset-backed securities (“ABS”), including commercial mortgage-backed securities, and repurchase agreements.

The Fund may invest in securities that represent interests in pools of mortgage loans or other assets assembled for sale to investors by various U.S. governmental agencies, government-related organizations and private issuers. These investments may include derivative securities such as collateralized mortgage obligations (“CMOs”) and ABS.

In addition, the Fund may invest in leveraged loans. The loans in which the Fund will invest are expected to be below-investment-grade quality and to bear interest at a floating rate that resets periodically.

The Fund may invest up to 20% of its net assets in below-investment grade, high-yield debt securities (commonly known as “junk bonds”), including bonds rated in default. A debt security is below investment grade when assigned a credit quality rating below BBB- by Standard & Poor’s or an equivalent rating by another NRSRO, or if unrated, considered to be of comparable credit quality by the Fund’s Advisor.

The Fund may also invest up to 25% of its net assets in foreign debt securities. Foreign debt securities include American Depositary Receipts (“ADRs”).

The Fund is “non-diversified,” which means it may invest a greater percentage of its assets in a particular issuer than a “diversified” fund.

The Fund uses a hedging technique that includes the purchase and sale of U.S. Treasury securities and related futures contracts to manage the duration of the Fund.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Non-Diversification Risk. Because the Fund may invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than a diversified fund.

Bond Market Risk. The market prices of bonds held by the Fund may fall.

Credit Risk. The credit quality of fixed-income securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.

Mortgage-Backed and Asset-Backed Securities Risk. The value of investments in mortgage-backed and asset-backed securities is subject to interest rate risk and credit risk. These securities are also subject to the risk that borrowers will prepay the principal on their loans more quickly than expected (prepayment risk) or more slowly than expected (extension risk), which will affect the yield, average life and price of the securities. In addition, faster than expected prepayments may cause the Fund to invest the prepaid principal in lower yielding securities and slower than expected prepayments may reduce the potential for the Fund to invest in higher yielding securities.

Mortgage-Backed Security Risk (Government-Sponsored Enterprises).  Debt and mortgage-backed securities issued by government-sponsored enterprises (“GSEs”) such as FNMA and FHLMC are neither insured nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. Government. Such securities are only supported by the credit of the applicable GSE. The U.S. government has provided financial support to FNMA and FHLMC, but there can be no assurance that it will support these or other GSEs in the future.

Leveraged Loan Risk. Leveraged loans are subject to the risks typically associated with debt securities, such as credit risk discussed above. In addition, leveraged loans, which typically hold a senior position in the capital structure of a borrower, are subject to the risk that a court could subordinate such loans to presently existing or future indebtedness or take other action detrimental to the holders of leveraged loans. Leveraged loans are also subject to the risk that the value of the collateral, if any, securing a loan may decline, be insufficient to meet the obligations of the borrower, or be difficult to liquidate. Some leveraged loans are not as easily purchased or sold as publicly-traded securities and others are illiquid, which may make it more difficult for the Fund to value them or dispose of them at an acceptable price. Leveraged loans are usually more credit sensitive than investment-grade securities.

Management Risk. The individual investments of the Fund may not perform as expected, due to credit, political or other risks and/ or the Fund’s portfolio management practices may not achieve the desired result.

Interest Rate Risk. A change in interest rates may adversely affect the value of fixed-income securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.

Junk Bond Risk. Investments in junk bonds can involve a substantial risk of loss. Junk bonds are considered to be speculative with respect to the issuer’s ability to pay interest and principal. These securities, which are rated below investment grade, have a higher risk of issuer default, are subject to greater price volatility than investment grade securities and may be illiquid.

Defaulted Bonds Risk. For bonds in default (rated “D” by Standard & Poor’s or the equivalent by another NRSRO), there is a significant risk that these bonds will not achieve full recovery.

Unrated Security Risk. Unrated securities may be less liquid than rated securities determined to be of comparable quality. When the Fund purchases unrated securities, it will depend on the Advisor’s analysis of credit risk without the assessment of an NRSRO.

Corporate and Taxable Municipal Bond Risk. For corporate and taxable municipal bonds, there is credit risk in addition to the interest rate risk that affects all fixed-income securities.

Trust Preferred Securities Risk. Trust preferred securities are preferred stocks issued by a special purpose trust subsidiary backed by subordinated debt of the corporate parent. Trust preferred securities are subject to unique risks, which include the fact that dividend payments will only be paid if interest payments on the underlying obligations are made, which interest payments are dependent on the financial condition of the parent corporation. There is also the risk that the underlying obligations, and thus the trust preferred securities, may be prepaid after a stated call date or as a result of certain tax or regulatory events, resulting in a lower yield to maturity. There can be no assurance as to the liquidity of trust preferred securities and the ability of holders of such securities to sell their holdings.

Asset-Backed Security Risk. The value of investments in asset-backed securities is subject to interest rate risk and credit risk. Asset-backed securities are also subject to prepayment risk and extension risk.

Collateralized Mortgage Obligation and Structured Asset-Backed Securities Risk. A CMO is a multiclass bond that is backed by a pool of mortgage loans or mortgage-backed securities. A structured ABS is a multiclass bond that is typically backed by a pool of auto loans, credit card receivables, home equity loans or student loans. A CMO or structured ABS is subject to interest rate risk, credit risk, prepayment risk and extension risk. In addition, if the Fund holds a class of a CMO or a structured ABS that is subordinated to other classes backed by the same pool of collateral, the likelihood that the Fund will receive payments of principal may be substantially limited.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from the differences between the regulations to which U.S. and foreign issuers and markets are subject, and the potential for foreign markets to be less liquid and more volatile than U.S. markets. Foreign securities include ADRs. Unsponsored ADRs involve additional risks because U.S. reporting requirements do not apply and the issuing bank will recover shareholder distribution costs from movement of share prices and payment of dividends.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall. ADRs indirectly bear currency risk because they represent an interest in securities that are not denominated in U.S. dollars.

Repurchase Agreement Risk. A repurchase agreement exposes the Fund to the risk that the party that sells the security may default on its obligation to repurchase it. The Fund may lose money because it cannot sell the security at the agreed-upon time and price or the security loses value before it can be sold.

Active Trading Strategy Risk. The Fund employs an active style that seeks to position the Fund with securities that offer the greatest price appreciation while minimizing risk. This style can result in higher turnover (exceeding 100%), may translate to higher transaction costs and may increase your tax liability.

Futures Contracts Risk. The value of a futures contract tends to increase and decrease in tandem with the value of the underlying instrument. The price of futures can be highly volatile; using them could lower total return, and the potential loss from futures can exceed the Fund’s initial investment in such contracts.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

Non-Diversification Risk. Because the Fund may invest a greater percentage of its assets in a particular issuer than a diversified fund, the gains or losses on a single bond may have greater impact on the Fund than a diversified fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class I shares has varied from year to year. The table compares the Fund’s performance over time with that of an index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart shows how the performance of the Class I shares has varied from year to year.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.calvert.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Calendar Year Total Return

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/09	5.73	%
Worst Quarter (of periods shown)	12/31/08	-3.55	%

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns
(as of 12-31-12)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Institutional | Calvert Bond Portfolio | Class I

Risk/Return:

rr_RiskReturnAbstract

Redemption fee (as a % of amount redeemed or exchanged within 7 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Management fees

rr_ManagementFeesOverAssets

0.45%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.11%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.56%

1 Year

rr_ExpenseExampleYear01

5,724

3 Years

rr_ExpenseExampleYear03

17,947

5 Years

rr_ExpenseExampleYear05

31,279

10 Years

rr_ExpenseExampleYear10

70,146

2003

rr_AnnualReturn2003

8.77%

2004

rr_AnnualReturn2004

6.61%

2005

rr_AnnualReturn2005

5.04%

2006

rr_AnnualReturn2006

4.95%

2007

rr_AnnualReturn2007

7.25%

2008

rr_AnnualReturn2008

(4.50%)

2009

rr_AnnualReturn2009

11.57%

2010

rr_AnnualReturn2010

6.80%

2011

rr_AnnualReturn2011

6.23%

2012

rr_AnnualReturn2012

8.27%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter (of periods shown)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

5.73%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter (of periods shown)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(3.55%)

1 Year

rr_AverageAnnualReturnYear01

8.27%

5 Years

rr_AverageAnnualReturnYear05

5.53%

10 Years

rr_AverageAnnualReturnYear10

6.02%

Institutional | Calvert Bond Portfolio | Return after taxes on distributions | Class I

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

6.54%

5 Years

rr_AverageAnnualReturnYear05

3.81%

10 Years

rr_AverageAnnualReturnYear10

4.14%

Institutional | Calvert Bond Portfolio | Return after taxes on distributions and sale of Fund shares | Class I

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

5.37%

5 Years

rr_AverageAnnualReturnYear05

3.71%

10 Years

rr_AverageAnnualReturnYear10

4.08%

Institutional | Calvert Bond Portfolio | Barclays U.S. Credit Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

9.37%

5 Years

rr_AverageAnnualReturnYear05

7.65%

10 Years

rr_AverageAnnualReturnYear10

6.23%

Institutional | Calvert Bond Portfolio | Lipper Corporate Debt Funds A Rated Average (reflects no deduction for taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

7.11%

5 Years

rr_AverageAnnualReturnYear05

6.31%

10 Years

rr_AverageAnnualReturnYear10

5.33%

XML

Retail | Calvert Moderate Allocation Fund

CALVERT MODERATE ALLOCATION FUND
Class  (Ticker):   A  (CMAAX)   C  (CMACX)

INVESTMENT OBJECTIVE

The Fund seeks long-term capital appreciation and growth of income,

with current income a secondary objective, consistent with the preservation of capital. This objective may be changed by the Fund’s Board of Trustees without shareholder approval.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 89 and “Reduced Sales Charges” on page 92 of this Prospectus, and under “Method of Distribution” on page 51 of the Fund’s Statement of Additional Information (“SAI”).

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Retail Calvert Moderate Allocation Fund		Class A	Class C
Maximum sales charge (load) on purchases (as a % of offering price)		4.75%	none
Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)	[1]	none	1.00%
Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)		2.00%	2.00%

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Annual Fund Operating Expenses Retail Calvert Moderate Allocation Fund

Class A

Class C

Advisory fee

none

none

Administrative fee

0.15%

0.15%

Distribution and service (12b-1) fees

0.25%

1.00%

Other expenses

0.32%

0.30%

Acquired fund fees and expenses

0.73%

0.73%

Total annual fund operating expenses

1.45%

2.18%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;
• your investment has a 5% return each year;
• the Fund’s operating expenses remain the same; and
• the estimated gross expenses of the underlying Calvert funds (or net expenses if subject to an expense limit for at least a year) are incorporated.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Expense Example Retail Calvert Moderate Allocation Fund (USD $)	1 Year	3 Years	5 Years	10 Years
Class A	616	912	1,230	2,128
Class C	321	682	1,170	2,513

Expense Example, No Redemption (USD $)	1 Year	3 Years	5 Years	10 Years
Retail Calvert Moderate Allocation Fund Class C	221	682	1,170	2,513

Portfolio Turnover

The Fund may pay transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). These transaction costs are also incurred by the underlying Calvert funds. A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 25% of its portfolio’s average value.

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

The Fund is a “fund of funds” that seeks to achieve its investment objective by investing in a portfolio of underlying Calvert fixed-income, equity and money market funds that meets the Fund’s investment criteria, including financial, sustainability and social responsibility factors.

The Fund invests in underlying Calvert funds in accordance with a stable target asset allocation determined by the Advisor. The Fund’s asset allocation strategy incorporates historical risk and return characteristics of various asset classes and correlations between asset classes to establish allocations intended to provide an optimal level of return for a given level of risk. Historical returns-based analysis and actual holdings data of the target underlying Calvert funds are then integrated to blend the styles of the underlying Calvert funds with the asset allocation policy.

The Fund intends to invest in shares of underlying Calvert funds and typically invests in underlying Calvert funds as follows:

50% to 80% of	In funds that invest primarily in equity secu-
Fund's net assets	rities (Calvert Equity Portfolio, Calvert
	Social Index Fund, Calvert Large Cap Core
	Portfolio, Calvert Capital Accumulation Fund,
	Calvert International Equity Fund, Calvert
	International Opportunities Fund, Calvert
	Emerging Markets Equity Fund, Calvert
	Global Alternative Energy Fund, Calvert
	Global Water Fund and Calvert Small Cap
	Fund)
20% to 50% of	In Calvert Bond Portfolio (which invests pri-
Fund's net assets	marily in fixed-income securities)
0% to 10% of Fund's	In Calvert Money Market Portfolio (which
net assets	invests primarily in money market instruments)

The Fund may also invest, to a limited extent, in (1) derivative instruments, including, but not limited to, index futures, options and swaps; and (2) exchange-traded funds. The Fund will use these instruments to facilitate the periodic rebalancing of the Fund’s portfolio to maintain its target asset allocation, to make tactical asset allocations and to assist in managing cash.

For information on the investment objectives, strategies and risks of the underlying Calvert funds, see the respective Fund Summaries of the underlying equity funds in this Prospectus, and see “Description of Underlying Funds” in this Prospectus, which describes the underlying fixed-income and money market funds (Calvert Bond Portfolio and Calvert Money Market Portfolio).

The Advisor may select new or different underlying Calvert funds other than those listed above without prior approval of or prior notice to shareholders.

The above asset allocation percentages are allocation targets. The Advisor has discretion to reallocate the Fund’s assets among underlying Calvert funds. The Advisor monitors the Fund’s allocation and may rebalance or reallocate the Fund’s assets (1) based on its view of economic and market factors and events or (2) to adjust for shifts in the style biases of the underlying funds. The Advisor also evaluates any necessary rebalancing to reflect different target asset class allocations based on changed economic and market conditions.

Sustainable and Socially Responsible Investing. Each underlying fund (other than Calvert Global Alternative Energy Fund and Calvert Global Water Fund) seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert Global Alternative Energy Fund will invest in ways consistent with Calvert’s philosophy that long-term rewards to investors will come from companies and other entities whose products, services, and methods contribute to a more sustainable future. Calvert Global Water Fund seeks to invest in a wide range of companies and other enterprises that demonstrate varying degrees of commitment and progress toward addressing key corporate responsibility and sustainability challenges.

Each underlying fund (other than Calvert Global Water Fund) has sustainable and socially responsible investment criteria that reflect specific types of companies in which the fund seeks to invest and seeks to avoid investing. Calvert Global Water Fund’s sustainable and socially responsible investment criteria reflect threshold responsibility standards used in determining whether a security qualifies as an investment for the fund, and specific types of companies in which the fund seeks to invest.

Investments for each underlying fund are first selected for financial soundness and then evaluated according to the fund’s sustainable and socially responsible investment criteria. Investments for each underlying fund must be consistent with the fund’s current investment criteria, including financial, sustainability and social responsibility factors, as well as threshold responsibility standards (for Calvert Global Water Fund only), the application of which is in the economic interest of the underlying fund and its shareholders.

Principal Risks

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Asset Allocation Risk. The Advisor’s selection of underlying funds and the allocation of Fund assets to those funds may cause the Fund to underperform. The Fund’s greater allocation to equity funds makes it more susceptible to risks associated with equity investments than fixed-income investments.

Management Risk. Individual investments of an underlying fund may not perform as expected, and the underlying fund’s portfolio management practices may not achieve the desired result.

Derivatives Risk. In general, a derivative is a financial contract whose value is based on the value of a financial asset (such as a stock, bond, or currency), a physical asset (such as gold), or a market index (such as the S&P 500 Index). Derivative instruments are subject to a number of risks, including the risk of changes in the market price of the underlying asset, credit risk with respect to the counterparty, and liquidity risk. The Fund’s use of certain derivatives may also have a leveraging effect, which may increase the volatility of the Fund and reduce its returns.

Exchange-Traded Fund (“ETF”) Risk. An ETF seeks to track the performance of an index by holding in its portfolio shares of all the companies, or a representative sample of the companies, that are components of a particular index. The risks of investment in ETFs typically reflect the risk of the types of securities in which the ETFs invest. In addition, when the Fund invests in an ETF, shareholders of the Fund bear their proportionate share of the ETF’s fees and expenses as well as their share of the Fund’s fees and expenses.

Equity Investments. The Fund shares the principal risks of equity securities held by the underlying funds, including the key risks below.

Stock Market Risk. The market prices of stocks held by the underlying funds may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Fixed-Income Investments. The Fund shares the principal risks of fixed-income securities held by the underlying funds, including the key risks below.

Bond Market Risk. The market prices of bonds held by the underlying funds may fall.

Interest Rate Risk. A change in interest rates may adversely affect the value of the securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.

Credit Risk. The credit quality of the securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.

Money Market Investments. The Fund shares the principal risks of money market securities held by the underlying funds, including the key risk below.

Money Market Risk. Yield will change in response to market interest rates; in general, as market rates go up, so will yield, and vice versa. Although the underlying fund tries to keep the value of its shares constant at $1.00 per share, changes in market rates could cause the value to decrease. Credit quality of the securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due. Credit risk, however, should be low for the underlying fund because it invests primarily in securities that are considered to be of high quality; the underlying fund also limits the amount it invests in any one issuer to try to lessen its exposure to credit risk.

Performance

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of a broad-based securities market index, a composite index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

The return for the Fund’s other Class of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Calendar Year Total Returns for Class A at NAV

	Quarter	Total
	Ended	Results
Best Quarter (of periods shown)	6/30/09	13.24	%
Worst Quarter (of periods shown)	12/31/08	-16.48	%

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Average Annual Total Returns
(as of 12/31/12) (with maximum
sales charge deducted)

Average Annual Total Returns Retail Calvert Moderate Allocation Fund		1 Year	5 Years	Since Inception	Inception Date
Class A		7.66%	0.47%	3.28%	Apr. 29, 2005
Class A Return after taxes on distributions		7.39%	(0.01%)	2.75%
Class A Return after taxes on distributions and sale of Fund shares		5.13%	0.19%	2.59%
Class C		11.16%	0.67%	3.10%	Apr. 29, 2005
Russell 3000 Index (reflects no deduction for fees, expenses or taxes)		16.42%	2.04%	5.36%
Moderate Allocation Composite Index (reflects no deduction for fees, expenses or taxes)	[1]	13.81%	2.76%	5.38%
Lipper Mixed-Asset Target Allocation Growth Funds Avg. (reflects no deduction for taxes)		12.63%	1.72%	4.74%

[1] The contingent deferred sales charge reduces over time.

[1] The Fund also shows the Moderate Allocation Composite Index (47% Russell 3000 Index; 18% Morgan Stanley Capital International Europe Australasia Far East Global Investable Market Index; 30% Barclays U.S. Credit Index; 5% Barclays 3-month T-Bill Bellwether Index) because it is more consistent with the Fund's portfolio construction process and represents a more accurate reflection of the Fund's anticipated risk and return patterns.

XML

Retail | Calvert Conservative Allocation Fund

CALVERT CONSERVATIVE ALLOCATION FUND
Class  (Ticker):   A  (CCLAX)   C  (CALCX)

INVESTMENT OBJECTIVE

The Fund seeks current income and capital appreciation, consistent with the preservation of capital. This objective may be changed by the Fund’s Board of Trustees without shareholder approval.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 89 and “Reduced Sales Charges” on page 92 of this Prospectus, and under “Method of Distribution” on page 51 of the Fund’s Statement of Additional Information (“SAI”).

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Retail Calvert Conservative Allocation Fund		Class A	Class C
Maximum sales charge (load) on purchases (as a % of offering price)		4.75%	none
Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)	[1]	none	1.00%
Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)		2.00%	2.00%

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Annual Fund Operating Expenses Retail Calvert Conservative Allocation Fund

Class A

Class C

Advisory fee

none

none

Administrative fee

0.15%

0.15%

Distribution and service (12b-1) fees

0.25%

1.00%

Other expenses

0.37%

0.36%

Acquired fund fees and expenses

0.65%

0.65%

Total annual fund operating expenses

1.42%

2.16%

Less fee waiver and/or expense reimbursement

^[1]

(0.33%)

Net Expenses

1.09%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;
• your investment has a 5% return each year;
• the Fund’s operating expenses remain the same;
• any Calvert expense limitation is in effect for the period indicated in the fee table above; and
• the estimated gross expenses of the underlying Calvert funds (or net expenses if subject to an expense limit for at least a year) are incorporated.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Expense Example Retail Calvert Conservative Allocation Fund (USD $)	1 Year	3 Years	5 Years	10 Years
Class A	581	872	1,185	2,069
Class C	319	676	1,159	2,493

Expense Example, No Redemption (USD $)	1 Year	3 Years	5 Years	10 Years
Retail Calvert Conservative Allocation Fund Class C	219	676	1,159	2,493

Portfolio Turnover

The Fund may pay transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). These transaction costs are also incurred by the underlying Calvert funds. A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 26% of its portfolio’s average value.

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

The Fund is a “fund of funds” that seeks to achieve its investment objective by investing in a portfolio of underlying Calvert fixed-income, equity and money market funds that meets the Fund’s investment criteria, including financial, sustainability and social responsibility factors.

The Fund invests in underlying Calvert funds in accordance with a stable target asset allocation determined by the Advisor. The Fund’s asset allocation strategy incorporates historical risk and return characteristics of various asset classes and correlations between asset classes to establish allocations intended to provide an optimal level of return for a given level of risk. Historical returns-based analysis and actual holdings data of the target underlying Calvert funds are then integrated to blend the styles of the underlying Calvert funds with the asset allocation policy.

The Fund intends to invest in shares of underlying Calvert funds and typically invests in underlying Calvert funds as follows:

60% to 80% of	In Calvert Bond Portfolio (which invests
Fund's net assets	primarily in fixed-income securities)
20% to 40% of	In funds that invest primarily in equity secu-
Fund's net assets	rities (Calvert Equity Portfolio, Calvert
	Social Index Fund, Calvert Large Cap Core
	Portfolio, Calvert Capital Accumulation Fund,
	Calvert International Equity Fund, Calvert
	International Opportunities Fund, Calvert
	Emerging Markets Equity Fund, Calvert
	Global Alternative Energy Fund, Calvert
	Global Water Fund and Calvert Small Cap
	Fund)
0% to 10% of Fund's	In Calvert Money Market Portfolio (which
net assets	invests primarily in money market instruments)

The Fund may also invest, to a limited extent, in (1) derivative instruments, including, but not limited to, index futures, options and swaps; and (2) exchange-traded funds. The Fund will use these instruments to facilitate the periodic rebalancing of the Fund’s portfolio to maintain its target asset allocation, to make tactical asset allocations and to assist in managing cash.

For information on the investment objectives, strategies and risks of the underlying Calvert funds, see the respective Fund Summaries of the underlying equity funds in this Prospectus, and see “Description of Underlying Funds” in this Prospectus, which describes the underlying fixed-income and money market funds (Calvert Bond Portfolio and Calvert Money Market Portfolio).

The Advisor may select new or different underlying Calvert funds other than those listed above without prior approval of or prior notice to shareholders.

The above asset allocation percentages are allocation targets. The Advisor has discretion to reallocate the Fund’s assets among underlying Calvert funds. The Advisor monitors the Fund’s allocation and may rebalance or reallocate the Fund’s assets (1) based on its view of economic and market factors and events or (2) to adjust for shifts in the style biases of the underlying funds. The Advisor also evaluates any necessary rebalancing to reflect different target asset class allocations based on changed economic and market conditions.

Sustainable and Socially Responsible Investing. Each underlying fund (other than Calvert Global Alternative Energy Fund and Calvert Global Water Fund) seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert Global Alternative Energy Fund will invest in ways consistent with Calvert’s philosophy that long-term rewards to investors will come from companies and other entities whose products, services, and methods contribute to a more sustainable future. Calvert Global Water Fund seeks to invest in a wide range of companies and other enterprises that demonstrate varying degrees of commitment and progress toward addressing key corporate responsibility and sustainability challenges.

Each underlying fund (other than Calvert Global Water Fund) has sustainable and socially responsible investment criteria that reflect specific types of companies in which the fund seeks to invest and seeks to avoid investing. Calvert Global Water Fund’s sustainable and socially responsible investment criteria reflect threshold responsibility standards used in determining whether a security qualifies as an investment for the fund, and specific types of companies in which the fund seeks to invest.

Investments for each underlying fund are first selected for financial soundness and then evaluated according to the fund’s sustainable and socially responsible investment criteria. Investments for each underlying fund must be consistent with the fund’s current investment criteria, including financial, sustainability and social responsibility factors, as well as threshold responsibility standards (for Calvert Global Water Fund only), the application of which is in the economic interest of the underlying fund and its shareholders.

Principal Risks

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Asset Allocation Risk. The Advisor’s selection of underlying funds and the allocation of Fund assets to those funds may cause the Fund to underperform. The Fund’s greater allocation to fixed-income funds makes it more susceptible to risks associated with fixed-income investments than equity investments.

Management Risk. Individual investments of an underlying fund may not perform as expected, and the underlying fund’s portfolio management practices may not achieve the desired result.

Derivatives Risk. In general, a derivative is a financial contract whose value is based on the value of a financial asset (such as a stock, bond, or currency), a physical asset (such as gold), or a market index (such as the S&P 500 Index). Derivative instruments are subject to a number of risks, including the risk of changes in the market price of the underlying asset, credit risk with respect to the counterparty, and liquidity risk. The Fund’s use of certain derivatives may also have a leveraging effect, which may increase the volatility of the Fund and reduce its returns.

Exchange-Traded Fund (“ETF”) Risk. An ETF seeks to track the performance of an index by holding in its portfolio shares of all the companies, or a representative sample of the companies, that are components of a particular index. The risks of investment in ETFs typically reflect the risk of the types of securities in which the ETFs invest. In addition, when the Fund invests in an ETF, shareholders of the Fund bear their proportionate share of the ETF’s fees and expenses as well as their share of the Fund’s fees and expenses.

Equity Investments. The Fund shares the principal risks of equity securities held by the underlying funds, including the key risks below.

Stock Market Risk. The market prices of stocks held by the underlying funds may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Fixed-Income Investments. The Fund shares the principal risks of fixed-income securities held by the underlying funds, including the key risks below.

Bond Market Risk. The market prices of bonds held by the underlying funds may fall.

Interest Rate Risk. A change in interest rates may adversely affect the value of the securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.

Credit Risk. The credit quality of the securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.

Money Market Investments. The Fund shares the principal risks of money market securities held by the underlying funds, including the key risk below.

Money Market Risk. Yield will change in response to market interest rates; in general, as market rates go up, so will yield, and vice versa. Although the underlying fund tries to keep the value of its shares constant at $1.00 per share, changes in market rates could cause the value to decrease. Credit quality of the securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due. Credit risk, however, should be low for the underlying fund because it invests primarily in securities that are considered to be of high quality; the underlying fund also limits the amount it invests in any one issuer to try to lessen its exposure to credit risk.

Performance

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of a broad-based securities market index, a composite index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

The return for the Fund’s other Class of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Calendar Year Total Returns for Class A at NAV

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	9/30/09	9.08	%
Worst Quarter (of periods shown)	12/31/08	-9.39	%

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for the other Class will vary.

Average Annual Total Returns
(as of 12/31/12) (with maximum
sales charge deducted)

Average Annual Total Returns Retail Calvert Conservative Allocation Fund		1 Year	5 Years	Since Inception	Inception Date
Class A		5.35%	3.10%	4.30%	Apr. 29, 2005
Class A Return after taxes on distributions		4.18%	1.96%	3.14%
Class A Return after taxes on distributions and sale of Fund shares		3.94%	2.05%	3.08%
Class C		8.48%	2.82%	3.67%	Apr. 29, 2005
Barclays U.S. Credit Index (reflects no deduction for fees, expenses or taxes)		9.37%	7.65%	6.41%
Conservative Allocation Composite Index (reflects no deduction for fees, expenses or taxes)	[1]	10.70%	4.86%	5.59%
Lipper Mixed-Asset Target Allocation Conservative Funds Avg. (reflects no deduction for taxes)		9.36%	3.84%	4.68%

[1] The contingent deferred sales charge reduces over time.

[1] The investment advisor has agreed to contractually limit direct ordinary operating expenses through January 31, 2014. This expense limitation does not limit the acquired fund fees and expenses paid indirectly by a shareholder. Direct ordinary operating expenses will not exceed 0.44% for Class A and 2.00% for Class C. Only the Board of Trustees of the Fund may terminate the Fund's expense limitation before the contractual period expires.

[1] The Fund also shows the Conservative Allocation Composite Index (22% Russell 3000 Index; 8% Morgan Stanley Capital International Europe Australasia Far East Global Investable Market Index; 60% Barclays U.S. Credit Index; 10% Barclays 3-month T-Bill Bellwether Index) because it is more consistent with the Fund's portfolio construction process and represents a more accurate reflection of the Fund's anticipated risk and return patterns.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

CALVERT SOCIAL INVESTMENT FUND

Prospectus Date

rr_ProspectusDate

Jan. 31, 2013

Retail | Calvert Aggressive Allocation Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

CALVERT AGGRESSIVE ALLOCATION FUND
Class  (Ticker):   A  (CAAAX)   C  (CAACX)

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term capital appreciation. This objective may be changed by the Fund's Board of Trustees without shareholder approval.

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 89 and “Reduced Sales Charges” on page 92 of this Prospectus, and under “Method of Distribution” on page 51 of the Fund’s Statement of Additional Information (“SAI”).

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a


% of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

January 31, 2014

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund may pay transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). These transaction costs are also incurred by the underlying Calvert funds. A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 24% of its portfolio’s average value.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

24.00%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

The contingent deferred sales charge reduces over time.

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

50,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;

• your investment has a 5% return each year;

• the Fund’s operating expenses remain the same;

• any Calvert expense limitation is in effect for the period indicated in the fee table above; and

• the estimated gross expenses of the underlying Calvert funds (or net expenses if subject to an expense limit for at least a year) are incorporated.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that seeks to achieve its investment objective by investing in a portfolio of underlying Calvert fixed-income, equity and money market funds that meets the Fund’s investment criteria, including financial, sustainability and social responsibility factors.

The Fund invests in underlying Calvert funds in accordance with a stable target asset allocation determined by the Advisor. The Fund’s asset allocation strategy incorporates historical risk and return characteristics of various asset classes and correlations between asset classes to establish allocations intended to provide an optimal level of return for a given level of risk. Historical returns-based analysis and actual holdings data of the target underlying Calvert funds are then integrated to blend the styles of the underlying Calvert funds with the asset allocation policy.

The Fund intends to invest in shares of underlying Calvert funds and typically invests in underlying Calvert funds as follows:

80% to 100% of	In funds that invest primarily in equity secu-
Fund's net assets	rities (Calvert Equity Portfolio, Calvert
	Social Index Fund, Calvert Large Cap Core
	Portfolio, Calvert Capital Accumulation Fund,
	Calvert International Equity Fund, Calvert
	International Opportunities Fund, Calvert
	Emerging Markets Equity Fund, Calvert
	Global Alternative Energy Fund, Calvert
	Global Water Fund and Calvert Small Cap
	Fund)
0% to 20% of	In Calvert Bond Portfolio (which invests pri-
Fund's net assets	marily in fixed-income securities)
0% to 5% of Fund's	In Calvert Money Market Portfolio (which
net assets	invests primarily in money market instruments)

The Fund may also invest, to a limited extent, in (1) derivative instruments, including, but not limited to, index futures, options and swaps; and (2) exchange-traded funds. The Fund will use these instruments to facilitate the periodic rebalancing of the Fund’s portfolio to maintain its target asset allocation, to make tactical asset allocations and to assist in managing cash.

For information on the investment objectives, strategies and risks of the underlying Calvert funds, see the respective Fund Summaries of the underlying equity funds in this Prospectus, and see “Description of Underlying Funds” in this Prospectus, which describes the underlying fixed-income and money market funds (Calvert Bond Portfolio and Calvert Money Market Portfolio).

The Advisor may select new or different underlying Calvert funds other than those listed above without prior approval of or prior notice to shareholders.

The above asset allocation percentages are allocation targets. The Advisor has discretion to reallocate the Fund’s assets among underlying Calvert funds. The Advisor monitors the Fund’s allocation and may rebalance or reallocate the Fund’s assets (1) based on its view of economic and market factors and events or (2) to adjust for shifts in the style biases of the underlying funds. The Advisor also evaluates any necessary rebalancing to reflect different target asset class allocations based on changed economic and market conditions.

Sustainable and Socially Responsible Investing. Each underlying fund (other than Calvert Global Alternative Energy Fund and Calvert Global Water Fund) seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert Global Alternative Energy Fund will invest in ways consistent with Calvert’s philosophy that long-term rewards to investors will come from companies and other entities whose products, services, and methods contribute to a more sustainable future. Calvert Global Water Fund seeks to invest in a wide range of companies and other enterprises that demonstrate varying degrees of commitment and progress toward addressing key corporate responsibility and sustainability challenges.

Each underlying fund (other than Calvert Global Water Fund) has sustainable and socially responsible investment criteria that reflect specific types of companies in which the fund seeks to invest and seeks to avoid investing. Calvert Global Water Fund’s sustainable and socially responsible investment criteria reflect threshold responsibility standards used in determining whether a security qualifies as an investment for the fund, and specific types of companies in which the fund seeks to invest.

Investments for each underlying fund are first selected for financial soundness and then evaluated according to the fund’s sustainable and socially responsible investment criteria. Investments for each underlying fund must be consistent with the fund’s current investment criteria, including financial, sustainability and social responsibility factors, as well as threshold responsibility standards (for Calvert Global Water Fund only), the application of which is in the economic interest of the underlying fund and its shareholders.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Asset Allocation Risk. The Advisor’s selection of underlying funds and the allocation of Fund assets to those funds may cause the Fund to underperform. The Fund’s greater allocation to equity funds makes it more susceptible to risks associated with equity investments than fixed-income investments.

Management Risk. Individual investments of an underlying fund may not perform as expected, and the underlying fund’s portfolio management practices may not achieve the desired result.

Derivatives Risk. In general, a derivative is a financial contract whose value is based on the value of a financial asset (such as a stock, bond, or currency), a physical asset (such as gold), or a market index (such as the S&P 500 Index). Derivative instruments are subject to a number of risks, including the risk of changes in the market price of the underlying asset, credit risk with respect to the counterparty, and liquidity risk. The Fund’s use of certain derivatives may also have a leveraging effect, which may increase the volatility of the Fund and reduce its returns.

Exchange-Traded Fund (“ETF”) Risk. An ETF seeks to track the performance of an index by holding in its portfolio shares of all the companies, or a representative sample of the companies, that are components of a particular index. The risks of investment in ETFs typically reflect the risk of the types of securities in which the ETFs invest. In addition, when the Fund invests in an ETF, shareholders of the Fund bear their proportionate share of the ETF’s fees and expenses as well as their share of the Fund’s fees and expenses.

Equity Investments. The Fund shares the principal risks of equity securities held by the underlying funds, including the key risks below.

Stock Market Risk. The market prices of stocks held by the underlying funds may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Fixed-Income Investments. The Fund shares the principal risks of fixed-income securities held by the underlying funds, including the key risks below.

Bond Market Risk. The market prices of bonds held by the underlying funds may fall.

Interest Rate Risk. A change in interest rates may adversely affect the value of the securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.

Credit Risk. The credit quality of the securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.

Money Market Investments. The Fund shares the principal risks of money market securities held by the underlying funds, including the key risk below.

Money Market Risk. Yield will change in response to market interest rates; in general, as market rates go up, so will yield, and vice versa. Although the underlying fund tries to keep the value of its shares constant at $1.00 per share, changes in market rates could cause the value to decrease. Credit quality of the securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due. Credit risk, however, should be low for the underlying fund because it invests primarily in securities that are considered to be of high quality; the underlying fund also limits the amount it invests in any one issuer to try to lessen its exposure to credit risk.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of a broad-based securities market index, a composite index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

The return for the Fund’s other Class of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart shows how the performance of the Class A shares has varied from year to year.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.calvert.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Calendar Year Total Returns for Class A at NAV

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	6/30/09	16.87	%
Worst Quarter (of periods shown)	12/31/08	-21.79	%

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Retail | Calvert Aggressive Allocation Fund | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.75%

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Advisory fee

rr_ManagementFeesOverAssets

none

Administrative fee

csif_AdministrativeFees

0.15

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.46%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.82%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.68%

Less fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

(0.43%)

^[2]

Net annual fund operating expenses

rr_NetExpensesOverAssets

1.25%

1 Year

rr_ExpenseExampleYear01

596

3 Years

rr_ExpenseExampleYear03

939

5 Years

rr_ExpenseExampleYear05

1,306

10 Years

rr_ExpenseExampleYear10

2,333

2006

rr_AnnualReturn2006

13.06%

2007

rr_AnnualReturn2007

5.22%

2008

rr_AnnualReturn2008

(37.32%)

2009

rr_AnnualReturn2009

26.18%

2010

rr_AnnualReturn2010

12.07%

2011

rr_AnnualReturn2011

(3.81%)

2012

rr_AnnualReturn2012

15.25%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter (of periods shown)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

16.87%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter (of periods shown)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(21.79%)

1 Year

rr_AverageAnnualReturnYear01

9.80%

5 Years

rr_AverageAnnualReturnYear05

(1.32%)

Since Inception

rr_AverageAnnualReturnSinceInception

2.25%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 30, 2005

Retail | Calvert Aggressive Allocation Fund | Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

1.00%

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Advisory fee

rr_ManagementFeesOverAssets

none

Administrative fee

csif_AdministrativeFees

0.15

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.54%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.82%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.51%

Less fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

^[2]

Net annual fund operating expenses

rr_NetExpensesOverAssets

1 Year

rr_ExpenseExampleYear01

354

3 Years

rr_ExpenseExampleYear03

782

5 Years

rr_ExpenseExampleYear05

1,335

10 Years

rr_ExpenseExampleYear10

2,846

1 Year

rr_ExpenseExampleNoRedemptionYear01

254

3 Years

rr_ExpenseExampleNoRedemptionYear03

782

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,335

10 Years

rr_ExpenseExampleNoRedemptionYear10

2,846

1 Year

rr_AverageAnnualReturnYear01

12.79%

5 Years

rr_AverageAnnualReturnYear05

(1.67%)

Since Inception

rr_AverageAnnualReturnSinceInception

1.60%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 30, 2005

Retail | Calvert Aggressive Allocation Fund | After Taxes on Distributions and Sales | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

6.52%

5 Years

rr_AverageAnnualReturnYear05

(1.17%)

Since Inception

rr_AverageAnnualReturnSinceInception

1.86%

Retail | Calvert Aggressive Allocation Fund | After Taxes on Distributions | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

9.69%

5 Years

rr_AverageAnnualReturnYear05

(1.55%)

Since Inception

rr_AverageAnnualReturnSinceInception

1.96%

Retail | Calvert Aggressive Allocation Fund | Russell 3000 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

16.42%

5 Years

rr_AverageAnnualReturnYear05

2.04%

Since Inception

rr_AverageAnnualReturnSinceInception

4.87%

Retail | Calvert Aggressive Allocation Fund | Aggressive Allocation Composite Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

16.17%

^[3]

5 Years

rr_AverageAnnualReturnYear05

1.32%

^[3]

Since Inception

rr_AverageAnnualReturnSinceInception

4.93%

^[3]

[1] The contingent deferred sales charge reduces over time.

[2] The investment advisor has agreed to contractually limit direct ordinary operating expenses through January 31, 2014. This expense limitation does not limit the acquired fund fees and expenses paid indirectly by a shareholder. Direct ordinary operating expenses will not exceed 0.43% for Class A and 2.00% for Class C. Only the Board of Trustees of the Fund may terminate the Fund's expense limitation before the contractual period expires.

[3] The Fund also shows the Aggressive Allocation Composite Index (64% Russell 3000 Index; 26% Morgan Stanley Capital International Europe Australasia Far East Global Investable Market Index; 10% Barclays U.S. Credit Index) because it is more consistent with the Fund's portfolio construction process and represents a more accurate reflection of the Fund's anticipated risk and return patterns.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

CALVERT SOCIAL INVESTMENT FUND

Prospectus Date

rr_ProspectusDate

Jan. 31, 2013

Retail | Calvert Moderate Allocation Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

CALVERT MODERATE ALLOCATION FUND
Class  (Ticker):   A  (CMAAX)   C  (CMACX)

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term capital appreciation and growth of income,

Objective, Secondary [Text Block]

rr_ObjectiveSecondaryTextBlock

with current income a secondary objective, consistent with the preservation of capital. This objective may be changed by the Fund’s Board of Trustees without shareholder approval.

Expense [Heading]

rr_ExpenseHeading

FEES AND EXPENSES OF THE FUND

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 89 and “Reduced Sales Charges” on page 92 of this Prospectus, and under “Method of Distribution” on page 51 of the Fund’s Statement of Additional Information (“SAI”).

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a
% of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The Fund may pay transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). These transaction costs are also incurred by the underlying Calvert funds. A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 25% of its portfolio’s average value.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

25.00%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

The contingent deferred sales charge reduces over time.

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

50,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;
• your investment has a 5% return each year;
• the Fund’s operating expenses remain the same; and
• the estimated gross expenses of the underlying Calvert funds (or net expenses if subject to an expense limit for at least a year) are incorporated.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund is a “fund of funds” that seeks to achieve its investment objective by investing in a portfolio of underlying Calvert fixed-income, equity and money market funds that meets the Fund’s investment criteria, including financial, sustainability and social responsibility factors.

The Fund invests in underlying Calvert funds in accordance with a stable target asset allocation determined by the Advisor. The Fund’s asset allocation strategy incorporates historical risk and return characteristics of various asset classes and correlations between asset classes to establish allocations intended to provide an optimal level of return for a given level of risk. Historical returns-based analysis and actual holdings data of the target underlying Calvert funds are then integrated to blend the styles of the underlying Calvert funds with the asset allocation policy.

The Fund intends to invest in shares of underlying Calvert funds and typically invests in underlying Calvert funds as follows:

50% to 80% of	In funds that invest primarily in equity secu-
Fund's net assets	rities (Calvert Equity Portfolio, Calvert
	Social Index Fund, Calvert Large Cap Core
	Portfolio, Calvert Capital Accumulation Fund,
	Calvert International Equity Fund, Calvert
	International Opportunities Fund, Calvert
	Emerging Markets Equity Fund, Calvert
	Global Alternative Energy Fund, Calvert
	Global Water Fund and Calvert Small Cap
	Fund)
20% to 50% of	In Calvert Bond Portfolio (which invests pri-
Fund's net assets	marily in fixed-income securities)
0% to 10% of Fund's	In Calvert Money Market Portfolio (which
net assets	invests primarily in money market instruments)

The Fund may also invest, to a limited extent, in (1) derivative instruments, including, but not limited to, index futures, options and swaps; and (2) exchange-traded funds. The Fund will use these instruments to facilitate the periodic rebalancing of the Fund’s portfolio to maintain its target asset allocation, to make tactical asset allocations and to assist in managing cash.

For information on the investment objectives, strategies and risks of the underlying Calvert funds, see the respective Fund Summaries of the underlying equity funds in this Prospectus, and see “Description of Underlying Funds” in this Prospectus, which describes the underlying fixed-income and money market funds (Calvert Bond Portfolio and Calvert Money Market Portfolio).

The Advisor may select new or different underlying Calvert funds other than those listed above without prior approval of or prior notice to shareholders.

The above asset allocation percentages are allocation targets. The Advisor has discretion to reallocate the Fund’s assets among underlying Calvert funds. The Advisor monitors the Fund’s allocation and may rebalance or reallocate the Fund’s assets (1) based on its view of economic and market factors and events or (2) to adjust for shifts in the style biases of the underlying funds. The Advisor also evaluates any necessary rebalancing to reflect different target asset class allocations based on changed economic and market conditions.

Sustainable and Socially Responsible Investing. Each underlying fund (other than Calvert Global Alternative Energy Fund and Calvert Global Water Fund) seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert Global Alternative Energy Fund will invest in ways consistent with Calvert’s philosophy that long-term rewards to investors will come from companies and other entities whose products, services, and methods contribute to a more sustainable future. Calvert Global Water Fund seeks to invest in a wide range of companies and other enterprises that demonstrate varying degrees of commitment and progress toward addressing key corporate responsibility and sustainability challenges.

Each underlying fund (other than Calvert Global Water Fund) has sustainable and socially responsible investment criteria that reflect specific types of companies in which the fund seeks to invest and seeks to avoid investing. Calvert Global Water Fund’s sustainable and socially responsible investment criteria reflect threshold responsibility standards used in determining whether a security qualifies as an investment for the fund, and specific types of companies in which the fund seeks to invest.

Investments for each underlying fund are first selected for financial soundness and then evaluated according to the fund’s sustainable and socially responsible investment criteria. Investments for each underlying fund must be consistent with the fund’s current investment criteria, including financial, sustainability and social responsibility factors, as well as threshold responsibility standards (for Calvert Global Water Fund only), the application of which is in the economic interest of the underlying fund and its shareholders.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Asset Allocation Risk. The Advisor’s selection of underlying funds and the allocation of Fund assets to those funds may cause the Fund to underperform. The Fund’s greater allocation to equity funds makes it more susceptible to risks associated with equity investments than fixed-income investments.

Management Risk. Individual investments of an underlying fund may not perform as expected, and the underlying fund’s portfolio management practices may not achieve the desired result.

Derivatives Risk. In general, a derivative is a financial contract whose value is based on the value of a financial asset (such as a stock, bond, or currency), a physical asset (such as gold), or a market index (such as the S&P 500 Index). Derivative instruments are subject to a number of risks, including the risk of changes in the market price of the underlying asset, credit risk with respect to the counterparty, and liquidity risk. The Fund’s use of certain derivatives may also have a leveraging effect, which may increase the volatility of the Fund and reduce its returns.

Exchange-Traded Fund (“ETF”) Risk. An ETF seeks to track the performance of an index by holding in its portfolio shares of all the companies, or a representative sample of the companies, that are components of a particular index. The risks of investment in ETFs typically reflect the risk of the types of securities in which the ETFs invest. In addition, when the Fund invests in an ETF, shareholders of the Fund bear their proportionate share of the ETF’s fees and expenses as well as their share of the Fund’s fees and expenses.

Equity Investments. The Fund shares the principal risks of equity securities held by the underlying funds, including the key risks below.

Stock Market Risk. The market prices of stocks held by the underlying funds may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Fixed-Income Investments. The Fund shares the principal risks of fixed-income securities held by the underlying funds, including the key risks below.

Bond Market Risk. The market prices of bonds held by the underlying funds may fall.

Interest Rate Risk. A change in interest rates may adversely affect the value of the securities. When interest rates rise, the value of fixed-income securities will generally fall. Longer-term securities are subject to greater interest rate risk.

Credit Risk. The credit quality of the securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due.

Money Market Investments. The Fund shares the principal risks of money market securities held by the underlying funds, including the key risk below.

Money Market Risk. Yield will change in response to market interest rates; in general, as market rates go up, so will yield, and vice versa. Although the underlying fund tries to keep the value of its shares constant at $1.00 per share, changes in market rates could cause the value to decrease. Credit quality of the securities may deteriorate, which could lead to default or bankruptcy of the issuer where the issuer becomes unable to pay its obligations when due. Credit risk, however, should be low for the underlying fund because it invests primarily in securities that are considered to be of high quality; the underlying fund also limits the amount it invests in any one issuer to try to lessen its exposure to credit risk.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of a broad-based securities market index, a composite index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

The return for the Fund’s other Class of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The bar chart shows how the performance of the Class A shares has varied from year to year.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.calvert.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Calendar Year Total Returns for Class A at NAV

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

	Quarter	Total
	Ended	Results
Best Quarter (of periods shown)	6/30/09	13.24	%
Worst Quarter (of periods shown)	12/31/08	-16.48	%

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns
(as of 12/31/12) (with maximum
sales charge deducted)

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Retail | Calvert Moderate Allocation Fund | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.75%

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Advisory fee

rr_ManagementFeesOverAssets

none

Administrative fee

csif_AdministrativeFees

0.15%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.32%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.73%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.45%

1 Year

rr_ExpenseExampleYear01

616

3 Years

rr_ExpenseExampleYear03

912

5 Years

rr_ExpenseExampleYear05

1,230

10 Years

rr_ExpenseExampleYear10

2,128

2006

rr_AnnualReturn2006

10.21%

2007

rr_AnnualReturn2007

5.50%

2008

rr_AnnualReturn2008

(29.05%)

2009

rr_AnnualReturn2009

21.92%

2010

rr_AnnualReturn2010

10.22%

2011

rr_AnnualReturn2011

(0.28%)

2012

rr_AnnualReturn2012

13.04%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter (of periods shown)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

13.24%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter (of periods shown)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(16.48%)

1 Year

rr_AverageAnnualReturnYear01

7.66%

5 Years

rr_AverageAnnualReturnYear05

0.47%

Since Inception

rr_AverageAnnualReturnSinceInception

3.28%

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 29, 2005

Retail | Calvert Moderate Allocation Fund | Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)

rr_MaximumDeferredSalesChargeOverOfferingPrice

1.00%

^[1]

Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)

rr_RedemptionFeeOverRedemption

2.00%

Advisory fee

rr_ManagementFeesOverAssets

none

Administrative fee

csif_AdministrativeFees

0.15%

Distribution and service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.30%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.73%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.18%

1 Year

rr_ExpenseExampleYear01

321

3 Years

rr_ExpenseExampleYear03

682

5 Years

rr_ExpenseExampleYear05

1,170

10 Years

rr_ExpenseExampleYear10

2,513

1 Year

rr_ExpenseExampleNoRedemptionYear01

221

3 Years

rr_ExpenseExampleNoRedemptionYear03

682

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,170

10 Years

rr_ExpenseExampleNoRedemptionYear10

2,513

1 Year

rr_AverageAnnualReturnYear01

11.16%

5 Years

rr_AverageAnnualReturnYear05

0.67%

Since Inception

rr_AverageAnnualReturnSinceInception

3.10%

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 29, 2005

Retail | Calvert Moderate Allocation Fund | Return after taxes on distributions | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

7.39%

5 Years

rr_AverageAnnualReturnYear05

(0.01%)

Since Inception

rr_AverageAnnualReturnSinceInception

2.75%

Retail | Calvert Moderate Allocation Fund | Return after taxes on distributions and sale of Fund shares | Class A

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

5.13%

5 Years

rr_AverageAnnualReturnYear05

0.19%

Since Inception

rr_AverageAnnualReturnSinceInception

2.59%

Retail | Calvert Moderate Allocation Fund | Russell 3000 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

16.42%

5 Years

rr_AverageAnnualReturnYear05

2.04%

Since Inception

rr_AverageAnnualReturnSinceInception

5.36%

Retail | Calvert Moderate Allocation Fund | Moderate Allocation Composite Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

13.81%

^[2]

5 Years

rr_AverageAnnualReturnYear05

2.76%

^[2]

Since Inception

rr_AverageAnnualReturnSinceInception

5.38%

^[2]

Retail | Calvert Moderate Allocation Fund | Lipper Mixed-Asset Target Allocation Growth Funds Avg. (reflects no deduction for taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

12.63%

5 Years

rr_AverageAnnualReturnYear05

1.72%

Since Inception

rr_AverageAnnualReturnSinceInception

4.74%

[1] The contingent deferred sales charge reduces over time.

[2] The Fund also shows the Moderate Allocation Composite Index (47% Russell 3000 Index; 18% Morgan Stanley Capital International Europe Australasia Far East Global Investable Market Index; 30% Barclays U.S. Credit Index; 5% Barclays 3-month T-Bill Bellwether Index) because it is more consistent with the Fund's portfolio construction process and represents a more accurate reflection of the Fund's anticipated risk and return patterns.

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Retail | Calvert Equity Portfolio

CALVERT EQUITY PORTFOLIO
Class  (Ticker):   A  (CSIEX)   B  (CSEBX)   C  (CSECX)   Y  (CIEYX)

INVESTMENT OBJECTIVE

The Fund seeks growth of capital through investment in stocks believed to offer opportunities for potential capital appreciation and which meet the Fund’s investment criteria, including financial, sustainability and social responsibility factors. This objective may be changed by the Fund's Board of Trustees without shareholder approval.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in Calvert mutual funds that are not money market funds. More information about these and other discounts is available from your financial professional and under “Choosing a Share Class” on page 89 and “Reduced Sales Charges” on page 92 of this Prospectus, and under “Method of Distribution” on page 58 of the Fund’s Statement of Additional Information (“SAI”).

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Retail Calvert Equity Portfolio		Class A	Class B	Class C	Class Y
Maximum sales charge (load) on purchases (as a % of offering price)		4.75%	none	none	none
Maximum deferred sales charge (load) (as a % of amount purchased or redeemed, whichever is lower)	[1]	none	5.00%	1.00%	none
Redemption fee (as a % of amount redeemed or exchanged within 30 days of purchase)		2.00%	2.00%	2.00%	2.00%

Annual Fund Operating Expenses (expenses that you pay each year as a % of the value of your investment)

Annual Fund Operating Expenses Retail Calvert Equity Portfolio	Class A	Class B	Class C	Class Y
Management fees	0.70%	0.70%	0.70%	0.70%
Distribution and service (12b-1) fees	0.25%	1.00%	1.00%	none
Other expenses	0.26%	0.39%	0.24%	0.12%
Acquired fund fees and expenses	0.01%	0.01%	0.01%	0.01%
Total annual fund operating expenses	1.22%	2.10%	1.95%	0.83%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that:

• you invest $10,000 in the Fund for the time periods indicated and then either redeem or hold your shares at the end of those periods;
• your investment has a 5% return each year; and
• the Fund’s operating expenses remain the same.

Although your actual costs may be higher or lower, under these assumptions your costs would be:

Expense Example Retail Calvert Equity Portfolio (USD $)	1 Year	3 Years	5 Years	10 Years
Class A	593	844	1,113	1,882
Class B	713	1,058	1,329	2,206
Class C	298	612	1,052	2,275
Class Y	85	265	460	1,025

Expense Example, No Redemption Retail Calvert Equity Portfolio (USD $)	1 Year	3 Years	5 Years	10 Years
Class B	213	658	1,129	2,206
Class C	198	612	1,052	2,275

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (“turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the “Example”, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 36% of its portfolio’s average value.

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

The Fund normally invests at least 80% of its net assets, including borrowings for investment purposes, in equity securities (common stock). The Fund will provide shareholders with at least 60 days’ notice before changing this 80% policy. The Fund invests primarily in common stocks of U.S. large-cap companies. The Fund defines large-cap companies as those whose market capitalization falls within the range of the Standard & Poor’s (“S&P”) 500 Index. As of December 31, 2012, the market capitalization of the S&P 500 Index companies ranged from $1.63 billion to $500 billion with a weighted median level of $56.8 billion and a weighted average level of $106.1 billion. The Fund normally seeks to have a weighted average market capitalization of at least $20 billion.

The Fund may also invest in mid-cap stocks and may invest up to 25% of its net assets in foreign stocks.

The Subadvisor looks for established companies with a history of steady earnings growth. The Subadvisor selects companies based on its opinion that the company has the ability to sustain growth through high profitability and that the stock is favorably priced with respect to those growth expectations.

Sustainable and Socially Responsible Investing. The Fund seeks to invest in companies and other enterprises that demonstrate positive environmental, social and governance performance as they address corporate responsibility and sustainability challenges. Calvert believes that there are long-term benefits in an investment philosophy that attaches material weight to the environment, workplace relations, human rights, Indigenous Peoples’ rights, community relations, product safety and impact, and corporate governance and business ethics. Calvert also believes that managing risks and opportunities related to these issues can contribute positively to company performance as well as to investment performance over time. The Fund has sustainable and socially responsible investment criteria that reflect specific types of companies in which the Fund seeks to invest and seeks to avoid investing.

Investments are first selected for financial soundness and then evaluated according to the Fund’s sustainable and socially responsible investment criteria. Investments must be consistent with the Fund’s current investment criteria, including financial, sustainability and social responsibility factors, the application of which is in the economic interest of the Fund and its shareholders.

Principal Risks

You could lose money on your investment in the Fund, or the Fund could underperform, because of the risks described below. An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Management Risk. Individual investments of the Fund may not perform as expected, and the Fund’s portfolio management practices may not achieve the desired result.

Stock Market Risk. The market prices of stocks held by the Fund may fall.

Common Stock Risk. Although common stocks have a history of long-term growth in value, their prices fluctuate based on changes in a company’s financial condition, on overall market and economic conditions, and on investors’ perception of a company’s well-being.

Large-Cap Company Risk. Large-cap companies may be unable to respond quickly to new competitive challenges such as changes in technology, and also may not be able to attain the high growth rate of successful smaller companies, especially during extended periods of economic expansion.

Mid-Cap Company Risk. Prices of mid-cap stocks can be more volatile than those of larger, more established companies. Mid-cap companies are more likely to have more limited product lines, fewer capital resources and less depth of management than larger companies.

Growth Company Risk. Prices of growth company securities may fall more than the overall equity markets due to changing economic, political or market conditions or disappointing growth company earnings results. Growth stocks also generally lack the dividends of some value stocks that can cushion stock prices in a falling market.

Foreign Securities Risk. Investing in foreign securities involves additional risks relating to political, social, and economic developments abroad. Other risks result from differences between regulations that apply to U.S. and foreign issuers and markets, and the potential for foreign markets to be less liquid and more volatile than U.S. markets.

Foreign Currency Risk. Securities that trade or are denominated in currencies other than the U.S. dollar may be adversely affected by fluctuations in currency exchange rates. When the U.S. dollar strengthens relative to a foreign currency, the U.S. dollar value of an investment denominated in that currency will typically fall.

Performance

The following bar chart and table show the Fund’s annual returns and its long-term performance, which give some indication of the risks of investing in the Fund. The bar chart shows how the performance of the Class A shares has varied from year to year. The table compares the Fund’s performance over time with that of an index and an average.

The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. For updated performance information, visit www.calvert.com.

Performance results for Class Y shares prior to 10/31/08 (the Class Y shares’ inception date) reflect the performance of Class A shares at net asset value. Actual Class Y share performance would have been higher than Class A share performance because Class Y, unlike Class A, has no Rule 12b-1 fees.

The return for each of the Fund’s other Classes of shares will differ from the Class A returns shown in the bar chart, depending upon the expenses of that Class. The bar chart does not reflect any sales charge that you may be required to pay upon purchase or redemption of the Fund’s shares. Any sales charge will reduce your return.

Calendar Year Total Returns for Class A at NAV

	Quarter	Total
	Ended	Return
Best Quarter (of periods shown)	6/30/09	17.97	%
Worst Quarter (of periods shown)	12/31/08	-24.39	%

The average total return table shows the Fund’s returns with the maximum sales charge deducted, and no sales charge has been applied to the indices used for comparison in the table.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your tax situation and may differ from those shown. The after-tax returns shown are not relevant to you if you hold your Fund shares through a tax-deferred arrangement such as a 401(k) plan or individual retirement account. The return after taxes on distributions and sale of Fund shares may be higher than the return before taxes because the calculation assumes that shareholders receive a tax benefit for capital losses incurred on the sale of their shares. After-tax returns are shown only for Class A shares; after-tax returns for other Classes will vary.

Average Annual Total Returns
(as of 12/31/12) (with maximum sales
charge deducted, if any)

Average Annual Total Returns Retail Calvert Equity Portfolio	1 Year	5 Years	10 Years
Class A	10.04%	1.64%	5.97%
Class A Return after taxes on distributions	10.01%	1.24%	5.57%
Class A Return after taxes on distributions and sale of Fund shares	6.56%	1.30%	5.17%
Class B	9.49%	1.53%	5.57%
Class C	13.69%	1.85%	5.67%
Class Y	15.96%	2.93%	6.64%
S&P 500 Index (reflects no deduction for fees, expenses or taxes)	16.00%	1.66%	7.10%
Lipper Large-Cap Growth Funds Avg. (reflects no deduction for taxes)	15.26%	1.19%	6.67%

[1] The contingent deferred sales charge reduces over time.