485BPOS

As filed with the Securities and Exchange Commission

on March 21, 2013

Securities Act File No. 33-68124

Investment Company Act File No. 811-7986

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON D.C. 20549

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	o
Pre-Effective Amendment No.	o

Post-Effective Amendment No. 35 x

and/or
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	o

Amendment No. 37 x

(Check appropriate box or boxes)

THE ALGER INSTITUTIONAL FUNDS

(Exact Name of Registrant as Specified in Charter)

360 Park Avenue South, New York, New York	10010
(Address of Principal Executive Offices)	(Zip Code)

Registrant’s Telephone Number, including Area Code: 212-806-8800

Hal Liebes

Fred Alger Management, Inc.

360 Park Avenue South

New York, NY 10010

(Name and Address of Agent for Service)

Copy to:

Gary L. Granik, Esq.

Stroock & Stroock & Lavan LLP

180 Maiden Lane

New York, NY 10038-4982

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

x immediately upon filing pursuant to paragraph (b)

o on [date] pursuant to paragraph (b)

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

o on [date] pursuant to paragraph (a)(1)

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

o on [date] pursuant to paragraph (a)(2) of Rule 485

If appropriate, check the following box:

oThe post effective amendment designates a new effective date for a previously filed post-effective amendment.

SIGNATURES

Pursuant to the  requirements  of the  Securities Act of 1933 and the Investment Company Act of 1940,  as  amended,  Registrant certifies that it meets all the requirements for effectiveness of this registration statement under Rule 485(b) under the Securities Act and has duly caused this Amendment to be signed on its behalf by the undersigned,  thereto duly authorized, in the City of New York and State of New York on the 21st day of March, 2013.

THE ALGER INSTITUTIONAL FUNDS

		By:	/s/ Hal Liebes
			Hal Liebes, President
ATTEST:	/s/ Lisa A. Moss
Lisa A. Moss, Assistant Secretary

Pursuant to the  requirements  of the Securities Act of 1933, this Amendment has been signed below by the following  persons in the  capacities  and on the dates indicated.

/s/ Hal Liebes	President (Principal	March 21, 2013
Hal Liebes	Executive Officer)
/s/ Michael D. Martins	Treasurer	March 21, 2013
Michael D. Martins
*	Trustee	March 21, 2013
Charles F. Baird, Jr.
*	Trustee	March 21, 2013
Roger P. Cheever
*	Trustee	March 21, 2013
Hilary M. Alger
*	Trustee	March 21, 2013
Lester L. Colbert, Jr.
*	Trustee	March 21, 2013
Nathan E. Saint-Amand
*	Trustee	March 21, 2013
Stephen E. O’Neil
*	Trustee	March 21, 2013
David Rosenberg

*BY: /s/ Hal Liebes

Hal Liebes

Attorney-in-Fact

EXHIBIT INDEX

Index No.	Description of Exhibit
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CAL	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase

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Alger Capital Appreciation Focus Fund | Alger Capital Appreciation Focus Fund

Alger Capital Appreciation Focus Fund

INVESTMENT OBJECTIVE

Alger Capital Appreciation Focus Fund seeks long-term capital appreciation.

FUND FEES AND EXPENSES

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 $25,000 in Class A Shares of the Alger Family of Funds, including the Fund. More information about these and other discounts is available from your financial professional and in "Purchasing and Redeeming Fund Shares" beginning on page A-2 of the Fund's Prospectus and the sections "Right of Accumulation (Class A Shares)" and "Letter of Intent (Class A Shares)" on page 20 of the Fund's Statement of Additional Information. "Other Expenses" below are estimated assuming $1 million in net assets. If actual net assets are less, the actual expense ratio will be higher.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Alger Capital Appreciation Focus Fund	Alger Capital Appreciation Focus Fund Class A		Alger Capital Appreciation Focus Fund Class C
Maximum sales charge (load) imposed on purchases as a % of offering price	5.25%		none
Maximum deferred sales charge (load) as a % of purchase price or redemption proceeds, whichever is lower	1.00%	[1]	1.00%
Redemption Fee (as a % of amount redeemed or exchanged within 30 days)	2.00%		2.00%

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

Annual Fund Operating Expenses Alger Capital Appreciation Focus Fund		Alger Capital Appreciation Focus Fund Class A	Alger Capital Appreciation Focus Fund Class C
Management Fees	[1]	0.71%	0.71%
Distribution and/or Service (12b-1) Fees		0.25%	1.00%
Other Expenses		0.92%	0.92%
Total Annual Fund Operating Expenses		1.88%	2.63%
Expense Reimbursement	[2]	0.58%	0.58%
Total Annual Fund Operating Expenses After Expense Reimbursement		1.30%	2.05%

EXAMPLE

The following examples are intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The examples assume that you invest $10,000 in the Fund for the time periods indicated, that your investment has a 5% return each year and that the Fund's operating expenses remain the same.

Although your actual costs may be higher or lower, based on these assumptions you would pay the following expenses if you redeemed your shares at the end of each period:

Expense Example Alger Capital Appreciation Focus Fund (USD $)	1 YEAR	3 YEARS	5 YEARS	10 YEARS
Alger Capital Appreciation Focus Fund Class A	650	1,032	1,437	2,566
Alger Capital Appreciation Focus Fund Class C	308	762	1,343	2,921

You would pay the following expenses if you did not redeem your shares:

Expense Example No Redemption Alger Capital Appreciation Focus Fund (USD $)	1 YEAR	3 YEARS	5 YEARS	10 YEARS
Alger Capital Appreciation Focus Fund Class A	650	1,032	1,437	2,566
Alger Capital Appreciation Focus Fund Class C	208	762	1,343	2,921

PORTFOLIO TURNOVER

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "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 examples, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 153.72% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGY

Fred Alger Management, Inc. believes companies undergoing Positive Dynamic Change offer the best investment opportunities. Positive Dynamic Change refers to companies realizing High Unit Volume Growth or companies undergoing Positive Lifecycle Change. High Unit Volume Growth companies are traditional growth companies experiencing, for example, significantly growing demand or market dominance. Positive Lifecycle Change companies are, for example, companies benefiting from regulatory change, a new product introduction or management change.

The Fund focuses on equity securities of companies of any capitalization that Fred Alger Management, Inc. believes demonstrate promising growth potential.

The Fund intends to invest a substantial portion of its assets in a small number of issuers, and may therefore concentrate its holdings in fewer business sectors or industries. Generally the Fund will hold less than 50 securities. The number of securities held by the Fund may occasionally exceed this range, including, but not limited to, when the portfolio manager is accumulating new positions, phasing out and replacing existing positions, or responding to unusual market conditions. In addition, the Fund will seek to have an annual portfolio turnover rate of less than 100%. From time to time, such as in situations described above, the portfolio turnover rate may exceed 100%.

The Fund can also invest in derivative instruments. The Fund currently expects that its primary use of derivatives will involve entering into forward currency contract to hedge the Fund's foreign currency exposure when it holds, or proposes to hold, non-U.S. dollar denominated securities.

PRINCIPAL RISKS

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing. The Fund's price per share will fluctuate due to changes in the market prices of its investments. Also, the Fund's investments may not grow as fast as the rate of inflation and stocks tend to be more volatile than some other investments you could make, such as bonds.

Prices of growth stocks tend to be higher in relation to their companies' earnings and may be more sensitive to market, political and economic developments than other stocks, making their prices more volatile. An investment in the Fund may be better suited to investors who seek long-term capital growth and can tolerate fluctuations in their investment's value.

A small investment in derivatives could have a potentially large impact on the Fund's performance. Forward currency contracts are subject to currency exchange rate risks and the risk of non-performance by the contract counterparty.

The following risks may also apply:

•  investing in companies of all capitalizations involves the risk that smaller issuers in which the Fund invests may have limited product lines or financial resources, or lack management depth.

•  it may be difficult or impossible to liquidate a security position at a time and price acceptable to the Fund because of the potentially less frequent trading of stocks of smaller market capitalization.

•  the Fund may have a more concentrated portfolio than other funds, so it may be more vulnerable to changes in the market value of a single issuer and may be more susceptible to risks associated with a single economic, political or regulatory occurrence than a fund that has a more diversified portfolio.

•  the Fund may have substantial holdings within a particular sector, and companies in similar industries may be similarly affected by particular economic or market events.

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

PERFORMANCE

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance. Class A and Class C Shares were not offered prior to December 31, 2012. Historical performance prior to December 31, 2012 is that of the Fund's Class I Shares. Previously, the Fund followed different investment strategies under the name "Alger Large Cap Growth Institutional Fund" and was managed by different portfolio managers. Performance prior to December 31, 2012 reflects those management styles and does not reflect the current investment personnel and strategies of the Fund. Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future. Updated performance information is available on the Fund's website www.alger.com.

ANNUAL TOTAL RETURN FOR CLASS I SHARES as of December 31 (%)

Best Quarter:
Q2 2009	17.17%
Worst Quarter:
Q4 2008	-28.17%

AVERAGE ANNUAL TOTAL RETURN AS OF DECEMBER 31, 2012

Average Annual Returns Alger Capital Appreciation Focus Fund	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years	Average Annual Returns, Since Inception	Average Annual Returns, Inception Date
Alger Capital Appreciation Focus Fund Class I	8.73%	(1.87%)	5.93%	6.95%	Nov. 08, 1993
After Taxes on Distributions Alger Capital Appreciation Focus Fund Class I	8.73%	(1.95%)	5.88%	5.57%
After Taxes on Distributions and Sale of Fund Shares Alger Capital Appreciation Focus Fund Class I	5.67%	(1.63%)	5.18%	5.36%
Russell 1000 Growth Index (reflects no deduction for fees, expenses or taxes)	15.26%	3.12%	7.52%	7.42%	Nov. 08, 1993

In the foregoing 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 an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

[1] Purchases of $1 million of Class A Shares at net asset value may be subject to a contingent deferred sales charge of 1.00% on redemptions made within 12 months of purchase.

[1] The Fund and Fred Alger Management, Inc. have adopted fee breakpoints for Alger Capital Appreciation Focus Fund. The management fee for assets in excess of $1 billion is .60%.

[2] Fred Alger Management, Inc. has contractually agreed to reimburse Fund expenses (excluding interest, taxes, brokerage, and extraordinary expenses) through February 28, 2014 to the extent necessary to limit the total annual fund operating expenses of the Fund's Class A Shares to 1.30%, and Class C Shares to 2.05%, of the class's average daily net assets. This expense reimbursement cannot be terminated.

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Alger Capital Appreciation Focus Fund | Alger Capital Appreciation Focus Fund

Alger Capital Appreciation Focus Fund

INVESTMENT OBJECTIVE

Alger Capital Appreciation Focus Fund seeks long-term capital appreciation.

FUND FEES AND EXPENSES

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. There are no sales charges on purchases or redemptions.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Alger Capital Appreciation Focus Fund	Alger Capital Appreciation Focus Fund Class I	Alger Capital Appreciation Focus Fund Class R
Shareholder Fees (fees paid directly from your investment)	none	none

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

Annual Fund Operating Expenses Alger Capital Appreciation Focus Fund		Alger Capital Appreciation Focus Fund Class I	Alger Capital Appreciation Focus Fund Class R
Management Fees*	[1][2]	0.71%	0.71%
Distribution (12b-1) Fees	[1]	none	0.50%
Other Expenses (including shareholder servicing fees of .25%)	[1]	1.12%	1.32%
Total Annual Fund Operating Expenses	[1]	1.83%	2.53%
Expense Reimbursement**	[1][3]	0.68%
Total Annual Fund Operating Expenses After Expense Reimbursement	[1]	1.15%	2.53%

EXAMPLE

The following 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, that your investment has a 5% return each year and that the Fund's operating expenses remain the same.

Although your actual costs may be higher or lower, based on these assumptions you would pay the following expenses whether or not you redeemed your shares at the end of each period:

Expense Example Alger Capital Appreciation Focus Fund (USD $)	1 YEAR	3 YEARS	5 YEARS	10 YEARS
Alger Capital Appreciation Focus Fund Class I	117	509	927	2,092
Alger Capital Appreciation Focus Fund Class R	256	788	1,345	2,866

PORTFOLIO TURNOVER

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "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 153.72% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGY

Fred Alger Management, Inc. believes companies undergoing Positive Dynamic Change offer the best investment opportunities. Positive Dynamic Change refers to companies realizing High Unit Volume Growth or companies undergoing Positive Lifecycle Change. High Unit Volume Growth companies are traditional growth companies experiencing, for example, significantly growing demand or market dominance. Positive Lifecycle Change companies are, for example, companies benefitting from regulatory change, a new product introduction or management change.

The Fund focuses on equity securities of companies of any capitalization that Fred Alger Management, Inc. believes demonstrate promising growth potential.

The Fund intends to invest a substantial portion of its assets in a small number of issuers, and may therefore concentrate its holdings in fewer business sectors or industries. Generally the Fund will hold less than 50 securities. The number of securities held by the Fund may occasionally exceed this range, including, but not limited to, when the portfolio manager is accumulating new positions, phasing out and replacing existing positions, or responding to unusual market conditions. In addition, the Fund will seek to have an annual portfolio turnover rate of less than 100%. From time to time, such as in situations described above, the portfolio turnover rate may exceed 100%.

The Fund can also invest in derivative instruments. The Fund currently expects that its primary use of derivatives will involve entering into forward currency contracts to hedge the Fund's foreign currency exposure when it holds, or proposes to hold, non-U.S. dollar denominated securities.

PRINCIPAL RISKS

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing. The Fund's price per share will fluctuate due to changes in the market prices of its investments. Also, the Fund's investments may not grow as fast as the rate of inflation and stocks tend to be more volatile than some other investments you could make, such as bonds.

Prices of growth stocks tend to be higher in relation to their companies' earnings and may be more sensitive to market, political and economic developments than other stocks, making their prices more volatile. An investment in the Fund may be better suited to investors who seek long-term capital growth and can tolerate fluctuations in their investment's value.

A small investment in derivatives could have a potentially large impact on the Fund's performance. Forward currency contracts are subject to currency exchange rate risks and the risk of non-performance by the contract counterparty.

The following risks may also apply:

•  investing in companies of all capitalizations involves the risk that smaller issuers in which the Fund invests may have limited product lines or financial resources, or lack management depth.

•  it may be difficult or impossible to liquidate a security position at a time and price acceptable to the Fund because of the potentially less frequent trading of stocks of smaller market capitalization.

•  the Fund may have a more concentrated portfolio than other funds, so it may be more vulnerable to changes in the market value of a single issuer and may be more susceptible to risks associated with a single economic, political or regulatory occurrence than a fund that has a more diversified portfolio.

•  the Fund may have substantial holdings within a particular sector, and companies in similar industries may be similarly affected by particular economic or market events.

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

PERFORMANCE

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance. Prior to December 31, 2012, the Fund followed different investment strategies under the name "Alger Large Cap Growth Institutional Fund" and was managed by different portfolio managers. Performance prior to December 31, 2012 reflects those management styles and does not reflect the current investment personnel and strategies of the Fund. Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future. Updated performance information is available on the Fund's website www.alger.com.

ANNUAL TOTAL RETURN FOR CLASS I SHARES as of December 31 (%)

Best Quarter:
Q2 2003	17.17%
Worst Quarter:
Q4 2008	-28.17%

AVERAGE ANNUAL TOTAL RETURN AS OF DECEMBER 31, 2012

Average Annual Returns Alger Capital Appreciation Focus Fund	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years		Average Annual Returns, Since Inception		Average Annual Returns, Inception Date
Alger Capital Appreciation Focus Fund Class I	8.73%	(1.87%)	5.93%		6.95%		Nov. 08, 1993
Alger Capital Appreciation Focus Fund Class R	7.98%	(2.48%)	5.34%	[1]	6.38%	[1]	Jan. 27, 2003
After Taxes on Distributions Alger Capital Appreciation Focus Fund Class I	8.73%	(1.95%)	5.88%		5.57%
After Taxes on Distributions and Sale of Fund Shares Alger Capital Appreciation Focus Fund Class I	5.67%	(1.63%)	5.18%		5.36%
Russell 1000 Growth Index (reflects no deduction for fees, expenses or taxes)	15.26%	3.12%	7.52%		7.42%		Nov. 08, 1993

In the foregoing 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 an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for Class R Shares, which are not shown, will vary from those shown for Class I Shares. A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

[1] The Annual Fund Operating Expenses are as of the fiscal year ended October 31, 2012, adjusted for fees currently in place.

[2] The Fund and Fred Alger Management, Inc. have adopted fee breakpoints for Alger Capital Appreciation Focus Fund. The management fee for assets over $1 billion is .60%.

[3] Fred Alger Management, Inc. has contractually agreed to reimburse Fund expenses (excluding interest, taxes, brokerage, and extraordinary expenses) through February 28, 2014 to the extent necessary to limit the total annual fund operating expenses of the Class I Shares of the Fund to 1.15% of the class's average daily net assets. This expense reimbursement cannot be terminated.

[1] Performance of the Fund's Class R Shares prior to January 27, 2003 reflects the performance of the Fund's Class I Shares, as adjusted with currently applicable operating expenses, which differ from historical charges and expenses.

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Label

Element

Value

Risk/Return:

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Risk/Return [Heading]

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Alger Mid Cap Growth Institutional Fund

Objective [Heading]

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INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

Alger Mid Cap Growth Institutional Fund seeks long-term capital appreciation.

Expense [Heading]

rr_ExpenseHeading

FUND FEES AND EXPENSES

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. There are no sales charges on purchases or redemptions

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 percentage 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 (or "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 232.99% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

232.99%

Expense Example [Heading]

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EXAMPLE

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The following 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 $10,000.00 in the Fund for the time periods indicated, that your investment has a 5% return each year and that the Fund's operating expenses remain the same.

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

Although your actual costs may be higher or lower, based on these assumptions you would pay the following expenses whether or not you redeemed your shares at the end of each period:

Strategy [Heading]

rr_StrategyHeading

PRINCIPAL INVESTMENT STRATEGY

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Fred Alger Management, Inc. believes companies undergoing Positive Dynamic Change offer the best investment opportunities. Positive Dynamic Change refers to companies realizing High Unit Volume Growth or companies undergoing Positive Lifecycle Change. High Unit Volume Growth companies are traditional growth companies experiencing, for example, significantly growing demand or market dominance. Positive Lifecycle Change companies are, for example, companies benefitting from regulatory change, a new product introduction or management change.

The Fund focuses on mid-sized companies that Fred Alger Management, Inc. believes demonstrate promising growth potential. Under normal circumstances, the Fund invests at least 80% of its net assets in equity securities of companies that, at the time of purchase of the securities, have total market capitalization within the range of companies included in the Russell Midcap Growth Index or the S&P MidCap 400 Index, as reported by the indexes as of the most recent quarter-end. Both indexes are designed to track the performance of medium-capitalization stocks. At December 31, 2012, the market capitalization of the companies in these indexes ranged from $350 million to $25 billion.

The Fund can also invest in derivative instruments. The Fund currently expects that its primary uses of derivatives will involve: (1) purchasing put and call options and selling (writing) covered put and call options, on securities and securities indexes, to increase gain, to hedge against the risk of unfavorable price movements in the underlying securities, or to provide diversification of risk, and (2) entering into forward currency contracts to hedge the Fund's foreign currency exposure when it holds, or proposes to hold, non-U.S. dollar denominated securities.

Risk [Heading]

rr_RiskHeading

PRINCIPAL RISKS

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing. The Fund's price per share will fluctuate due to changes in the market prices of its investments. Also, the Fund's investments may not grow as fast as the rate of inflation and stocks tend to be more volatile than some other investments you could make, such as bonds.

Prices of growth stocks tend to be higher in relation to their companies' earnings and may be more sensitive to market, political and economic developments than other stocks, making their prices more volatile. An investment in the Fund may be better suited to investors who seek long-term capital growth and can tolerate fluctuations in their investment's value.

A small investment in derivatives could have a potentially large impact on the Fund's performance. When purchasing options, the Fund bears the risk that if the market value of the underlying security does not move to a level that would make exercise of the option profitable, the option will expire unexercised. When a call option written by the Fund is exercised, the Fund will not participate in any increase in the underlying security's value above the exercise price. When a put option written by the Fund is exercised, the Fund will be required to purchase the underlying security at a price in excess of its market value. Use of options on securities indexes is subject to the risk that trading in the options may be interrupted if trading in certain securities included in the index is interrupted, the risk that price movements in the Fund's portfolio securities may not correlate precisely with movements in the level of an index, and the risk that Fred Alger Management, Inc. may not predict correctly movements in the direction of a particular market or of the stock market generally. Because certain options may require settlement in cash, the Fund may be forced to liquidate portfolio securities to meet settlement obligations. Forward currency contracts are subject to currency exchange rate risks and the risk of non-performance by the contract counterparty.

The following risks may also apply:

•  there may be greater risk in investing in medium-capitalization companies rather than larger, more established companies owing to such factors as inexperienced management and limited product lines or financial resources.

•  it may be difficult or impossible to liquidate a security position at a time and price acceptable to the Fund owing to the potentially less frequent trading of stocks of smaller market capitalization.

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

Risk Lose Money [Text]

rr_RiskLoseMoney

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank 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 the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance. Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future. Updated performance information is available on the Fund's website www.alger.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.alger.com

Performance Past Does Not Indicate Future [Text]

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Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

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ANNUAL TOTAL RETURN FOR CLASS I SHARES as of December 31 (%)

Bar Chart Closing [Text Block]

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Best Quarter:
Q2 2003	20.09%
Worst Quarter:
Q4 2008	-32.88%

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2003

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

20.09%

Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(32.88%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

In the foregoing 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.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for Class R Shares, which are not shown, will vary from those shown for Class I Shares.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

In the foregoing 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 an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for Class R Shares, which are not shown, will vary from those shown for Class I Shares. A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURN AS OF DECEMBER 31, 2012

Russell MidCap Growth Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

15.81%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

3.23%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

10.32%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

8.37%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 08, 1993

Alger MidCap Growth Institutional Fund Class I

Risk/Return:

rr_RiskReturnAbstract

Shareholder Fees (fees paid directly from your investment)

rr_MaximumAccountFeeOverAssets

none

Management Fees

rr_ManagementFeesOverAssets

0.76%

^[1]

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses (including shareholder servicing fees of .25%)

rr_OtherExpensesOverAssets

0.47%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.23%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

125

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

390

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

676

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

1,489

Annual Return 2003

rr_AnnualReturn2003

45.66%

Annual Return 2004

rr_AnnualReturn2004

12.07%

Annual Return 2005

rr_AnnualReturn2005

10.32%

Annual Return 2006

rr_AnnualReturn2006

9.51%

Annual Return 2007

rr_AnnualReturn2007

34.56%

Annual Return 2008

rr_AnnualReturn2008

(58.74%)

Annual Return 2009

rr_AnnualReturn2009

51.40%

Annual Return 2010

rr_AnnualReturn2010

19.32%

Annual Return 2011

rr_AnnualReturn2011

(7.75%)

Annual Return 2012

rr_AnnualReturn2012

16.24%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

16.24%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(4.38%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.81%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

11.33%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 08, 1993

Alger MidCap Growth Institutional Fund Class I | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

16.14%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(4.42%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

6.64%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

8.73%

Alger MidCap Growth Institutional Fund Class I | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

10.56%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(3.69%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

6.32%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

8.57%

Alger MidCap Growth Institutional Fund Class R

Risk/Return:

rr_RiskReturnAbstract

Shareholder Fees (fees paid directly from your investment)

rr_MaximumAccountFeeOverAssets

none

Management Fees

rr_ManagementFeesOverAssets

0.76%

^[1]

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.50%

Other Expenses (including shareholder servicing fees of .25%)

rr_OtherExpensesOverAssets

0.50%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.76%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

179

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

554

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

954

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,073

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

15.63%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(4.88%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.27%

^[2]

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

10.78%

^[2]

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 27, 2003

[1] The Fund and Fred Alger Management, Inc. have adopted fee breakpoints for Alger Mid Cap Growth Institutional Fund. The management fee for assets in excess of $1 billion is .70%.

[2] Performance of the Fund's Class R Shares prior to January 27, 2003 reflects the performance of the Fund's Class I Shares, as adjusted with currently applicable operating expenses, which differ from historical charges and expenses.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Alger Capital Appreciation Focus Fund

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

Alger Capital Appreciation Focus Fund seeks long-term capital appreciation.

Expense [Heading]

rr_ExpenseHeading

FUND FEES AND EXPENSES

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 $25,000 in Class A Shares of the Alger Family of Funds, including the Fund. More information about these and other discounts is available from your financial professional and in "Purchasing and Redeeming Fund Shares" beginning on page A-2 of the Fund's Prospectus and the sections "Right of Accumulation (Class A Shares)" and "Letter of Intent (Class A Shares)" on page 20 of the Fund's Statement of Additional Information. "Other Expenses" below are estimated assuming $1 million in net assets. If actual net assets are less, the actual expense ratio will be higher.

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 percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2014-02-28

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 (or "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 examples, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 153.72% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

153.72%

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

"Other Expenses" below are estimated assuming $1 million in net assets.

Expense Example [Heading]

rr_ExpenseExampleHeading

EXAMPLE

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The following examples are intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The examples assume that you invest $10,000 in the Fund for the time periods indicated, that your investment has a 5% return each year and that the Fund's operating expenses remain the same.

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

Although your actual costs may be higher or lower, based on these assumptions you would pay the following expenses if you redeemed your shares at the end of each period:

Expense Example, No Redemption, By Year, Caption [Text]

rr_ExpenseExampleNoRedemptionByYearCaption

You would pay the following expenses if you did not redeem your shares:

Strategy [Heading]

rr_StrategyHeading

PRINCIPAL INVESTMENT STRATEGY

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Fred Alger Management, Inc. believes companies undergoing Positive Dynamic Change offer the best investment opportunities. Positive Dynamic Change refers to companies realizing High Unit Volume Growth or companies undergoing Positive Lifecycle Change. High Unit Volume Growth companies are traditional growth companies experiencing, for example, significantly growing demand or market dominance. Positive Lifecycle Change companies are, for example, companies benefiting from regulatory change, a new product introduction or management change.

The Fund focuses on equity securities of companies of any capitalization that Fred Alger Management, Inc. believes demonstrate promising growth potential.

The Fund intends to invest a substantial portion of its assets in a small number of issuers, and may therefore concentrate its holdings in fewer business sectors or industries. Generally the Fund will hold less than 50 securities. The number of securities held by the Fund may occasionally exceed this range, including, but not limited to, when the portfolio manager is accumulating new positions, phasing out and replacing existing positions, or responding to unusual market conditions. In addition, the Fund will seek to have an annual portfolio turnover rate of less than 100%. From time to time, such as in situations described above, the portfolio turnover rate may exceed 100%.

The Fund can also invest in derivative instruments. The Fund currently expects that its primary use of derivatives will involve entering into forward currency contract to hedge the Fund's foreign currency exposure when it holds, or proposes to hold, non-U.S. dollar denominated securities.

Risk [Heading]

rr_RiskHeading

PRINCIPAL RISKS

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing. The Fund's price per share will fluctuate due to changes in the market prices of its investments. Also, the Fund's investments may not grow as fast as the rate of inflation and stocks tend to be more volatile than some other investments you could make, such as bonds.

Prices of growth stocks tend to be higher in relation to their companies' earnings and may be more sensitive to market, political and economic developments than other stocks, making their prices more volatile. An investment in the Fund may be better suited to investors who seek long-term capital growth and can tolerate fluctuations in their investment's value.

A small investment in derivatives could have a potentially large impact on the Fund's performance. Forward currency contracts are subject to currency exchange rate risks and the risk of non-performance by the contract counterparty.

The following risks may also apply:

•  investing in companies of all capitalizations involves the risk that smaller issuers in which the Fund invests may have limited product lines or financial resources, or lack management depth.

•  it may be difficult or impossible to liquidate a security position at a time and price acceptable to the Fund because of the potentially less frequent trading of stocks of smaller market capitalization.

•  the Fund may have a more concentrated portfolio than other funds, so it may be more vulnerable to changes in the market value of a single issuer and may be more susceptible to risks associated with a single economic, political or regulatory occurrence than a fund that has a more diversified portfolio.

•  the Fund may have substantial holdings within a particular sector, and companies in similar industries may be similarly affected by particular economic or market events.

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

Risk Lose Money [Text]

rr_RiskLoseMoney

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

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

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

PERFORMANCE

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance. Class A and Class C Shares were not offered prior to December 31, 2012. Historical performance prior to December 31, 2012 is that of the Fund's Class I Shares. Previously, the Fund followed different investment strategies under the name "Alger Large Cap Growth Institutional Fund" and was managed by different portfolio managers. Performance prior to December 31, 2012 reflects those management styles and does not reflect the current investment personnel and strategies of the Fund. Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future. Updated performance information is available on the Fund's website www.alger.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.alger.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURN FOR CLASS I SHARES as of December 31 (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter:
Q2 2009	17.17%
Worst Quarter:
Q4 2008	-28.17%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

17.17%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(28.17%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

In the foregoing 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.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

In the foregoing 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 an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURN AS OF DECEMBER 31, 2012

Russell 1000 Growth Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

15.26%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

3.12%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.52%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

7.42%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 08, 1993

Alger Capital Appreciation Focus Fund Class I

Risk/Return:

rr_RiskReturnAbstract

Annual Return 2003

rr_AnnualReturn2003

34.37%

Annual Return 2004

rr_AnnualReturn2004

4.80%

Annual Return 2005

rr_AnnualReturn2005

11.70%

Annual Return 2006

rr_AnnualReturn2006

4.64%

Annual Return 2007

rr_AnnualReturn2007

18.84%

Annual Return 2008

rr_AnnualReturn2008

(47.25%)

Annual Return 2009

rr_AnnualReturn2009

40.43%

Annual Return 2010

rr_AnnualReturn2010

13.80%

Annual Return 2011

rr_AnnualReturn2011

(0.73%)

Annual Return 2012

rr_AnnualReturn2012

8.73%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

8.73%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(1.87%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

5.93%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

6.95%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 08, 1993

Alger Capital Appreciation Focus Fund Class I | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

8.73%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(1.95%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

5.88%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

5.57%

Alger Capital Appreciation Focus Fund Class I | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

5.67%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(1.63%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

5.18%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

5.36%

Alger Capital Appreciation Focus Fund Class A

Risk/Return:

rr_RiskReturnAbstract

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

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.25%

Maximum deferred sales charge (load) as a % of purchase price or redemption proceeds, whichever is lower

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[1]

Redemption Fee (as a percentage of Amount Redeemed)

rr_RedemptionFeeOverRedemption

(2.00%)

Management Fees

rr_ManagementFeesOverAssets

0.71%

^[2]

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses (including shareholder servicing fees of .25%)

rr_OtherExpensesOverAssets

0.92%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.88%

Fee Waiver or Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

(0.58%)

^[3]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_NetExpensesOverAssets

1.30%

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 $25,000 in Class A Shares of the Alger Family of Funds, including the Fund.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

25,000

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

650

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

1,032

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,437

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,566

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

650

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

1,032

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,437

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

2,566

Alger Capital Appreciation Focus Fund Class C

Risk/Return:

rr_RiskReturnAbstract

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

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) as a % of purchase price or redemption proceeds, whichever is lower

rr_MaximumDeferredSalesChargeOverOther

1.00%

Redemption Fee (as a percentage of Amount Redeemed)

rr_RedemptionFeeOverRedemption

(2.00%)

Management Fees

rr_ManagementFeesOverAssets

0.71%

^[2]

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other Expenses (including shareholder servicing fees of .25%)

rr_OtherExpensesOverAssets

0.92%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.63%

Fee Waiver or Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

(0.58%)

^[3]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_NetExpensesOverAssets

2.05%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

308

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

762

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,343

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,921

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

208

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

762

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,343

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

2,921

[1] Purchases of $1 million of Class A Shares at net asset value may be subject to a contingent deferred sales charge of 1.00% on redemptions made within 12 months of purchase.

[2] The Fund and Fred Alger Management, Inc. have adopted fee breakpoints for Alger Capital Appreciation Focus Fund. The management fee for assets in excess of $1 billion is .60%.

[3] Fred Alger Management, Inc. has contractually agreed to reimburse Fund expenses (excluding interest, taxes, brokerage, and extraordinary expenses) through February 28, 2014 to the extent necessary to limit the total annual fund operating expenses of the Fund's Class A Shares to 1.30%, and Class C Shares to 2.05%, of the class's average daily net assets. This expense reimbursement cannot be terminated.

XML

Alger Small Cap Growth Institutional Fund | Alger Small Cap Growth Institutional Fund

Alger Small Cap Growth Institutional Fund

INVESTMENT OBJECTIVE

Alger Small Cap Growth Institutional Fund seeks long-term capital appreciation.

FUND FEES AND EXPENSES

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. There are no sales charges on purchases or redemptions.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Alger Small Cap Growth Institutional Fund	Alger SmallCap Growth Institutional Fund Class I	Alger SmallCap Growth Institutional Fund Class R
Shareholder Fees (fees paid directly from your investment)	none	none

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

Annual Fund Operating Expenses Alger Small Cap Growth Institutional Fund		Alger SmallCap Growth Institutional Fund Class I	Alger SmallCap Growth Institutional Fund Class R
Management Fees	[1]	0.81%	0.81%
Distribution (12b-1) Fees		none	0.50%
Other Expenses (including shareholder servicing fees of .25%)		0.42%	0.42%
Total Annual Fund Operating Expenses		1.23%	1.73%

EXAMPLE

The following 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, that your investment has a 5% return each year and that the Fund's operating expenses remain the same.

Although your actual costs may be higher or lower, based on these assumptions you would pay the following expenses whether or not you redeemed your shares at the end of each period:

Expense Example Alger Small Cap Growth Institutional Fund (USD $)	1 YEAR	3 YEARS	5 YEARS	10 YEARS
Alger SmallCap Growth Institutional Fund Class I	125	390	676	1,489
Alger SmallCap Growth Institutional Fund Class R	176	545	939	2,041

PORTFOLIO TURNOVER

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "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 72.43% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGY

Fred Alger Management, Inc. believes companies undergoing Positive Dynamic Change offer the best investment opportunities. Positive Dynamic Change refers to companies realizing High Unit Volume Growth or companies undergoing Positive Lifecycle Change. High Unit Volume Growth companies are traditional growth companies experiencing, for example, significantly growing demand or market dominance. Positive Lifecycle Change companies are, for example, companies benefitting from regulatory change, a new product introduction or management change.

The Fund focuses on small, fast-growing companies that Fred Alger Management, Inc. believes offer innovative products, services or technologies to a rapidly expanding marketplace. Under normal circumstances, the Fund invests at least 80% of its net assets in equity securities of companies that, at the time of purchase of the securities, have total market capitalization within the range of companies included in the Russell 2000 Growth Index or the S&P SmallCap 600 Index, as reported by the indexes as of the most recent quarter-end. Both indexes are broad indexes of small capitalization stocks. At December 31, 2012, the market capitalization of the companies in these indexes ranged from $27 million to $4.7 billion.

PRINCIPAL RISKS

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing. The Fund's price per share will fluctuate due to changes in the market prices of its investments. Also, the Fund's investments may not grow as fast as the rate of inflation and stocks tend to be more volatile than some other investments you could make, such as bonds.

Prices of growth stocks tend to be higher in relation to their companies' earnings and may be more sensitive to market, political and economic developments than other stocks, making their prices more volatile. An investment in the Fund may be better suited to investors who seek long-term capital growth and can tolerate fluctuations in their investment's value.

The following risks also apply:

•  there may be greater risk in investing in smaller, less-seasoned companies rather than larger, more-established companies owing to such factors as inexperienced management and limited product lines or financial resources.

•  it may be difficult or impossible to liquidate a security position at a time and price acceptable to the Fund owing to the potentially less frequent trading of stocks of smaller market capitalization.

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

PERFORMANCE

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance. Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future. Updated performance information is available on the Fund's website www.alger.com.

ANNUAL TOTAL RETURN FOR CLASS I SHARES as of December 31 (%)

Best Quarter:
Q2 2009	20.34%
Worst Quarter:
Q4 2008	-27.26%

AVERAGE ANNUAL TOTAL RETURN AS OF DECEMBER 31, 2012

Average Annual Returns Alger Small Cap Growth Institutional Fund	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years		Average Annual Returns, Since Inception		Average Annual Returns, Inception Date
Alger SmallCap Growth Institutional Fund Class I	12.43%	1.29%	10.74%		8.70%		Nov. 08, 1993
Alger SmallCap Growth Institutional Fund Class R	11.85%	0.80%	10.22%	[1]	8.17%	[1]	Jan. 27, 2003
After Taxes on Distributions Alger SmallCap Growth Institutional Fund Class I	10.56%	0.82%	10.48%		7.77%
After Taxes on Distributions and Sale of Fund Shares Alger SmallCap Growth Institutional Fund Class I	10.58%	1.09%	9.62%		7.39%
Russell 2000 Growth Index (reflects no deduction for fees, expenses or taxes)	14.59%	3.49%	9.80%		5.80%		Nov. 08, 1993

In the foregoing 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 an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for Class R Shares, which are not shown, will vary from those shown for Class I Shares. A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

[1] The Fund and Fred Alger Management, Inc. have adopted fee breakpoints for Alger Small Cap Growth Institutional Fund. The management fee for assets in excess of $1 billion is .75%.

[1] Performance of the Fund's Class R Shares prior to January 27, 2003 reflects the performance of the Fund's Class I Shares, as adjusted with currently applicable operating expenses, which differ from historical charges and expenses.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Alger Capital Appreciation Institutional Fund

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

Alger Capital Appreciation Institutional Fund seeks long-term capital appreciation.

Expense [Heading]

rr_ExpenseHeading

FUND FEES AND EXPENSES

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. There are no sales charges on purchases or redemptions.

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 percentage 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 (or "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 137.16% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

137.16%

Expense Example [Heading]

rr_ExpenseExampleHeading

EXAMPLE

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The following 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, that your investment has a 5% return each year and that the Fund's operating expenses remain the same.

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

Although your actual costs may be higher or lower, based on these assumptions you would pay the following expenses whether or not you redeemed your shares at the end of each period:

Strategy [Heading]

rr_StrategyHeading

PRINCIPAL INVESTMENT STRATEGY

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Fred Alger Management, Inc. believes companies undergoing Positive Dynamic Change offer the best investment opportunities. Positive Dynamic Change refers to companies realizing High Unit Volume Growth or companies undergoing Positive Lifecycle Change. High Unit Volume Growth companies are traditional growth companies experiencing, for example, significantly growing demand or market dominance. Positive Lifecycle Change companies are, for example, companies benefitting from regulatory change, a new product introduction or management change.

Under normal market circumstances, the Fund invests at least 85% of its net assets, plus any borrowings for investment purposes, in equity securities of companies of any market capitalization that Fred Alger Management, Inc. believes demonstrate promising growth potential.

The Fund can leverage, that is, borrow money to buy additional securities. By borrowing money, the Fund has the potential to increase its returns if the increase in the value of the securities purchased exceeds the cost of borrowing, including interest paid on the money borrowed.

The Fund can also invest in derivative instruments. The Fund currently expects that its primary use of derivatives will involve entering into forward currency contracts to hedge the Fund's foreign currency exposure when it holds, or proposes to hold, non-U.S. dollar denominated securities.

Risk [Heading]

rr_RiskHeading

PRINCIPAL RISKS

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing. The Fund's price per share will fluctuate due to changes in the market prices of its investments. Also, the Fund's investments may not grow as fast as the rate of inflation and stocks tend to be more volatile than some other investments you could make, such as bonds.

Prices of growth stocks tend to be higher in relation to their companies' earnings and may be more sensitive to market, political and economic developments than other stocks, making their prices more volatile. An investment in the Fund may be better suited to investors who seek long-term capital growth and can tolerate fluctuations in their investment's value.

A small investment in derivatives could have a potentially large impact on the Fund's performance. Forward currency contracts are subject to currency exchange rate risks and the risk of non-performance by the contract counterparty.

The following risks also apply:

•  investing in companies of all capitalizations involves the risk that smaller issuers in which the Fund invests may have limited product lines or financial resources, or lack management depth.

•  it may be difficult or impossible to liquidate a security position at a time and price acceptable to the Fund because of the potentially less frequent trading of stocks of smaller market capitalization.

•  the cost of borrowing money to leverage may exceed the returns for the securities purchased or the securities purchased may actually go down in value; thus, the Fund's net asset value can decrease more quickly than if the Fund had not borrowed.

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

Risk Lose Money [Text]

rr_RiskLoseMoney

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank 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 the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance. Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future. Updated performance information is available on the Fund's website www.alger.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.alger.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURN FOR CLASS I SHARES as of December 31 (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter:
Q2 2009	20.56%
Worst Quarter:
Q4 2008	-21.96%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

20.56%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(21.96%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

In the foregoing 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.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for Class R Shares, which are not shown, will vary from those shown for Class I Shares.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

In the foregoing 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 an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for Class R Shares, which are not shown, will vary from those shown for Class I Shares. A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURN AS OF DECEMBER 31, 2012

Russell 1000 Growth Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

15.26%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

3.12%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.52%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

7.42%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 08, 1993

Russell 3000 Growth Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

15.21%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

3.15%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.69%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

7.15%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 08, 1993

Alger Capital Appreciation Institutional Fund Class I

Risk/Return:

rr_RiskReturnAbstract

Shareholder Fees (fees paid directly from your investment)

rr_MaximumAccountFeeOverAssets

none

Management Fees

rr_ManagementFeesOverAssets

0.81%

^[1]

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses (including shareholder servicing fees of .25%)

rr_OtherExpensesOverAssets

0.38%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.19%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

121

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

378

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

654

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

1,443

Annual Return 2003

rr_AnnualReturn2003

34.24%

Annual Return 2004

rr_AnnualReturn2004

8.03%

Annual Return 2005

rr_AnnualReturn2005

14.74%

Annual Return 2006

rr_AnnualReturn2006

18.23%

Annual Return 2007

rr_AnnualReturn2007

31.63%

Annual Return 2008

rr_AnnualReturn2008

(43.89%)

Annual Return 2009

rr_AnnualReturn2009

49.12%

Annual Return 2010

rr_AnnualReturn2010

13.48%

Annual Return 2011

rr_AnnualReturn2011

(1.03%)

Annual Return 2012

rr_AnnualReturn2012

18.11%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

18.11%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

2.11%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

11.14%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

11.08%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 08, 1993

Alger Capital Appreciation Institutional Fund Class I | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

16.85%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

1.65%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

10.88%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

9.03%

Alger Capital Appreciation Institutional Fund Class I | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

12.30%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

1.58%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

9.87%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

8.57%

Alger Capital Appreciation Institutional Fund Class R

Risk/Return:

rr_RiskReturnAbstract

Shareholder Fees (fees paid directly from your investment)

rr_MaximumAccountFeeOverAssets

none

Management Fees

rr_ManagementFeesOverAssets

0.81%

^[1]

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.50%

Other Expenses (including shareholder servicing fees of .25%)

rr_OtherExpensesOverAssets

0.38%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.69%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

172

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

533

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

918

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

1,998

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

17.56%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

1.59%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

10.57%

^[2]

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

10.52%

^[2]

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 27, 2003

[1] The Fund and Fred Alger Management, Inc. have adopted fee breakpoints for Alger Capital Appreciation Institutional Fund. The management fee for assets in excess of $2 billion is .65%, with an additional breakpoint of 0.60% for assets in excess of $4 billion.

[2] Performance of the Fund's Class R Shares prior to January 27, 2003 reflects the performance of the Fund's Class I Shares, as adjusted with currently applicable operating expenses, which differ from historical charges and expenses.

XML

Alger Capital Appreciation Institutional Fund | Alger Capital Appreciation Institutional Fund

Alger Capital Appreciation Institutional Fund

INVESTMENT OBJECTIVE

Alger Capital Appreciation Institutional Fund seeks long-term capital appreciation.

FUND FEES AND EXPENSES

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. There are no sales charges on purchases or redemptions.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Alger Capital Appreciation Institutional Fund	Alger Capital Appreciation Institutional Fund Class I	Alger Capital Appreciation Institutional Fund Class R
Shareholder Fees (fees paid directly from your investment)	none	none

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

Annual Fund Operating Expenses Alger Capital Appreciation Institutional Fund		Alger Capital Appreciation Institutional Fund Class I	Alger Capital Appreciation Institutional Fund Class R
Management Fees	[1]	0.81%	0.81%
Distribution (12b-1) Fees		none	0.50%
Other Expenses (including shareholder servicing fees of .25%)		0.38%	0.38%
Total Annual Fund Operating Expenses		1.19%	1.69%

EXAMPLE

The following 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, that your investment has a 5% return each year and that the Fund's operating expenses remain the same.

Although your actual costs may be higher or lower, based on these assumptions you would pay the following expenses whether or not you redeemed your shares at the end of each period:

Expense Example Alger Capital Appreciation Institutional Fund (USD $)	1 YEAR	3 YEARS	5 YEARS	10 YEARS
Alger Capital Appreciation Institutional Fund Class I	121	378	654	1,443
Alger Capital Appreciation Institutional Fund Class R	172	533	918	1,998

PORTFOLIO TURNOVER

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "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 137.16% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGY

Fred Alger Management, Inc. believes companies undergoing Positive Dynamic Change offer the best investment opportunities. Positive Dynamic Change refers to companies realizing High Unit Volume Growth or companies undergoing Positive Lifecycle Change. High Unit Volume Growth companies are traditional growth companies experiencing, for example, significantly growing demand or market dominance. Positive Lifecycle Change companies are, for example, companies benefitting from regulatory change, a new product introduction or management change.

Under normal market circumstances, the Fund invests at least 85% of its net assets, plus any borrowings for investment purposes, in equity securities of companies of any market capitalization that Fred Alger Management, Inc. believes demonstrate promising growth potential.

The Fund can leverage, that is, borrow money to buy additional securities. By borrowing money, the Fund has the potential to increase its returns if the increase in the value of the securities purchased exceeds the cost of borrowing, including interest paid on the money borrowed.

The Fund can also invest in derivative instruments. The Fund currently expects that its primary use of derivatives will involve entering into forward currency contracts to hedge the Fund's foreign currency exposure when it holds, or proposes to hold, non-U.S. dollar denominated securities.

PRINCIPAL RISKS

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing. The Fund's price per share will fluctuate due to changes in the market prices of its investments. Also, the Fund's investments may not grow as fast as the rate of inflation and stocks tend to be more volatile than some other investments you could make, such as bonds.

Prices of growth stocks tend to be higher in relation to their companies' earnings and may be more sensitive to market, political and economic developments than other stocks, making their prices more volatile. An investment in the Fund may be better suited to investors who seek long-term capital growth and can tolerate fluctuations in their investment's value.

A small investment in derivatives could have a potentially large impact on the Fund's performance. Forward currency contracts are subject to currency exchange rate risks and the risk of non-performance by the contract counterparty.

The following risks also apply:

•  investing in companies of all capitalizations involves the risk that smaller issuers in which the Fund invests may have limited product lines or financial resources, or lack management depth.

•  it may be difficult or impossible to liquidate a security position at a time and price acceptable to the Fund because of the potentially less frequent trading of stocks of smaller market capitalization.

•  the cost of borrowing money to leverage may exceed the returns for the securities purchased or the securities purchased may actually go down in value; thus, the Fund's net asset value can decrease more quickly than if the Fund had not borrowed.

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

PERFORMANCE

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance. Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future. Updated performance information is available on the Fund's website www.alger.com.

ANNUAL TOTAL RETURN FOR CLASS I SHARES as of December 31 (%)

Best Quarter:
Q2 2009	20.56%
Worst Quarter:
Q4 2008	-21.96%

AVERAGE ANNUAL TOTAL RETURN AS OF DECEMBER 31, 2012

Average Annual Returns Alger Capital Appreciation Institutional Fund	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years		Average Annual Returns, Since Inception		Average Annual Returns, Inception Date
Alger Capital Appreciation Institutional Fund Class I	18.11%	2.11%	11.14%		11.08%		Nov. 08, 1993
Alger Capital Appreciation Institutional Fund Class R	17.56%	1.59%	10.57%	[1]	10.52%	[1]	Jan. 27, 2003
After Taxes on Distributions Alger Capital Appreciation Institutional Fund Class I	16.85%	1.65%	10.88%		9.03%
After Taxes on Distributions and Sale of Fund Shares Alger Capital Appreciation Institutional Fund Class I	12.30%	1.58%	9.87%		8.57%
Russell 1000 Growth Index (reflects no deduction for fees, expenses or taxes)	15.26%	3.12%	7.52%		7.42%		Nov. 08, 1993
Russell 3000 Growth Index (reflects no deduction for fees, expenses or taxes)	15.21%	3.15%	7.69%		7.15%		Nov. 08, 1993

In the foregoing 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 an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for Class R Shares, which are not shown, will vary from those shown for Class I Shares. A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

[1] The Fund and Fred Alger Management, Inc. have adopted fee breakpoints for Alger Capital Appreciation Institutional Fund. The management fee for assets in excess of $2 billion is .65%, with an additional breakpoint of 0.60% for assets in excess of $4 billion.

[1] Performance of the Fund's Class R Shares prior to January 27, 2003 reflects the performance of the Fund's Class I Shares, as adjusted with currently applicable operating expenses, which differ from historical charges and expenses.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Prospectus Date	rr_ProspectusDate	Mar. 01, 2013

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Alger Capital Appreciation Focus Fund

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

Alger Capital Appreciation Focus Fund seeks long-term capital appreciation.

Expense [Heading]

rr_ExpenseHeading

FUND FEES AND EXPENSES

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. There are no sales charges on purchases or redemptions. "Other Expenses" below are estimated assuming $1 million in net assets. If actual net assets are less, the actual expense ratio will be higher.

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 percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2014-02-28

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 (or "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 examples, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 153.72% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

153.72%

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

"Other Expenses" below are estimated assuming $1 million in net assets. If actual net assets are less, the actual expense ratio will be higher.

Expense Example [Heading]

rr_ExpenseExampleHeading

EXAMPLE

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The following 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, that your investment has a 5% return each year and that the Fund's operating expenses remain the same.

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

Although your actual costs may be higher or lower, based on these assumptions you would pay the following expenses regardless of whether you redeemed your shares at the end of each period:

Strategy [Heading]

rr_StrategyHeading

PRINCIPAL INVESTMENT STRATEGY

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Fred Alger Management, Inc. believes companies undergoing Positive Dynamic Change offer the best investment opportunities. Positive Dynamic Change refers to companies realizing High Unit Volume Growth or companies undergoing Positive Lifecycle Change. High Unit Volume Growth Companies are traditional growth companies experiencing, for example, significantly growing demand or market dominance. Positive Lifecycle Change companies are, for example, companies benefiting from regulatory change, a new product introduction or management change.

The Fund focuses on equity securities of companies of any capitalization that Fred Alger Management, Inc. believes demonstrate promising growth potential.

The Fund intends to invest a substantial portion of its assets in a small number of issuers, and may therefore concentrate its holdings in fewer business sectors or industries. Generally the Fund will hold less than 50 securities. The number of securities held by the Fund may occasionally exceed this range, including, but not limited to, when the portfolio manager is accumulating new positions, phasing out and replacing existing positions, or responding to unusual market conditions. In addition, the Fund will seek to have an annual portfolio turnover rate of less than 100%. From time to time, such as in situations described above, the portfolio turnover rate may exceed 100%.

The Fund can also invest in derivative instruments. The Fund currently expects that its primary use of derivatives will involve entering into forward currency contract to hedge the Fund's foreign currency exposure when it holds, or proposes to hold, non-U.S. dollar denominated securities.

Risk [Heading]

rr_RiskHeading

PRINCIPAL RISKS

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing. The Fund's price per share will fluctuate due to changes in the market prices of its investments. Also, the Fund's investments may not grow as fast as the rate of inflation and stocks tend to be more volatile than some other investments you could make, such as bonds.

Prices of growth stocks tend to be higher in relation to their companies' earnings and may be more sensitive to market, political and economic developments than other stocks, making their prices more volatile. An investment in the Fund may be better suited to investors who seek long-term capital growth and can tolerate fluctuations in their investment's value.

A small investment in derivatives could have a potentially large impact on the Fund's performance. Forward currency contracts are subject to currency exchange rate risks and the risk of non-performance by the contract counterparty.

The following risks may also apply:

•  investing in companies of all capitalizations involves the risk that smaller issuers in which the Fund invests may have limited product lines or financial resources, or lack management depth.

•  it may be difficult or impossible to liquidate a security position at a time and price acceptable to the Fund because of the potentially less frequent trading of stocks of smaller market capitalization.

•  the Fund may have a more concentrated portfolio than other funds, so it may be more vulnerable to changes in the market value of a single issuer and may be more susceptible to risks associated with a single economic, political or regulatory occurrence than a fund that has a more diversified portfolio.

•  the Fund may have substantial holdings within a particular sector, and companies in similar industries may be similarly affected by particular economic or market events.

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

Risk Lose Money [Text]

rr_RiskLoseMoney

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

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

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

PERFORMANCE

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance. Class Z Shares were not offered prior to December 31, 2012. Historical performance prior to December 31, 2012 is that of the Fund's Class I Shares. Previously, the Fund followed different investment strategies under the name "Alger Large Cap Growth Institutional Fund" and was managed by different portfolio managers. Performance prior to December 31, 2012 reflects those management styles and does not reflect the current investment personnel and strategies of the Fund. Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future. Updated performance information is available on the Fund's website www.alger.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.alger.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURN FOR CLASS I SHARES as of December 31 (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter:
Q2 2003	17.17%
Worst Quarter:
Q4 2008	-28.17%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2003

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

17.17%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(28.17%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

In the foregoing 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.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

In the foregoing 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 an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURN AS OF DECEMBER 31, 2012

Russell 1000 Growth Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

15.26%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

3.12%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.52%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

7.42%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 08, 1993

Alger Capital Appreciation Focus Fund Class Z

Risk/Return:

rr_RiskReturnAbstract

Shareholder Fees (fees paid directly from your investment)

rr_MaximumAccountFeeOverAssets

none

Management Fees

rr_ManagementFeesOverAssets

0.71%

^[1]

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses (including shareholder servicing fees of .25%)

rr_OtherExpensesOverAssets

2.22%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.93%

Fee Waiver or Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

(2.04%)

^[2]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_NetExpensesOverAssets

0.89%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

91

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

714

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,362

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

3,106

Annual Return 2003

rr_AnnualReturn2003

34.37%

Annual Return 2004

rr_AnnualReturn2004

4.80%

Annual Return 2005

rr_AnnualReturn2005

11.70%

Annual Return 2006

rr_AnnualReturn2006

4.64%

Annual Return 2007

rr_AnnualReturn2007

18.84%

Annual Return 2008

rr_AnnualReturn2008

(47.25%)

Annual Return 2009

rr_AnnualReturn2009

40.43%

Annual Return 2010

rr_AnnualReturn2010

13.80%

Annual Return 2011

rr_AnnualReturn2011

(0.73%)

Annual Return 2012

rr_AnnualReturn2012

8.73%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

8.73%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(1.87%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

5.93%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

6.95%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 08, 1993

Alger Capital Appreciation Focus Fund Class Z | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

8.73%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(1.95%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

5.88%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

5.57%

Alger Capital Appreciation Focus Fund Class Z | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

5.67%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(1.63%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

5.18%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

5.36%

[1] The Fund and Fred Alger Management, Inc. have adopted fee breakpoints for Alger Capital Appreciation Focus Fund. The management fee for assets in excess of $1 billion is .60%.

[2] Fred Alger Management, Inc. has contractually agreed to reimburse Fund expenses (excluding interest, taxes, brokerage, and extraordinary expenses) through February 28, 2014 to the extent necessary to limit the total annual fund operating expenses of the Class Z Shares of the Fund to .89% of the class's average daily net assets. This expense reimbursement cannot be terminated.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Alger Small Cap Growth Institutional Fund

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

Alger Small Cap Growth Institutional Fund seeks long-term capital appreciation.

Expense [Heading]

rr_ExpenseHeading

FUND FEES AND EXPENSES

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. There are no sales charges on purchases or redemptions.

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 percentage 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 (or "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 72.43% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

72.43%

Expense Example [Heading]

rr_ExpenseExampleHeading

EXAMPLE

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The following 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, that your investment has a 5% return each year and that the Fund's operating expenses remain the same.

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

Although your actual costs may be higher or lower, based on these assumptions you would pay the following expenses whether or not you redeemed your shares at the end of each period:

Strategy [Heading]

rr_StrategyHeading

PRINCIPAL INVESTMENT STRATEGY

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Fred Alger Management, Inc. believes companies undergoing Positive Dynamic Change offer the best investment opportunities. Positive Dynamic Change refers to companies realizing High Unit Volume Growth or companies undergoing Positive Lifecycle Change. High Unit Volume Growth companies are traditional growth companies experiencing, for example, significantly growing demand or market dominance. Positive Lifecycle Change companies are, for example, companies benefitting from regulatory change, a new product introduction or management change.

The Fund focuses on small, fast-growing companies that Fred Alger Management, Inc. believes offer innovative products, services or technologies to a rapidly expanding marketplace. Under normal circumstances, the Fund invests at least 80% of its net assets in equity securities of companies that, at the time of purchase of the securities, have total market capitalization within the range of companies included in the Russell 2000 Growth Index or the S&P SmallCap 600 Index, as reported by the indexes as of the most recent quarter-end. Both indexes are broad indexes of small capitalization stocks. At December 31, 2012, the market capitalization of the companies in these indexes ranged from $27 million to $4.7 billion.

Risk [Heading]

rr_RiskHeading

PRINCIPAL RISKS

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing. The Fund's price per share will fluctuate due to changes in the market prices of its investments. Also, the Fund's investments may not grow as fast as the rate of inflation and stocks tend to be more volatile than some other investments you could make, such as bonds.

Prices of growth stocks tend to be higher in relation to their companies' earnings and may be more sensitive to market, political and economic developments than other stocks, making their prices more volatile. An investment in the Fund may be better suited to investors who seek long-term capital growth and can tolerate fluctuations in their investment's value.

The following risks also apply:

•  there may be greater risk in investing in smaller, less-seasoned companies rather than larger, more-established companies owing to such factors as inexperienced management and limited product lines or financial resources.

•  it may be difficult or impossible to liquidate a security position at a time and price acceptable to the Fund owing to the potentially less frequent trading of stocks of smaller market capitalization.

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

Risk Lose Money [Text]

rr_RiskLoseMoney

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a deposit of a bank 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 the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance. Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future. Updated performance information is available on the Fund's website www.alger.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.alger.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURN FOR CLASS I SHARES as of December 31 (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter:
Q2 2009	20.34%
Worst Quarter:
Q4 2008	-27.26%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

20.34%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(27.26%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

In the foregoing 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.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for Class R Shares, which are not shown, will vary from those shown for Class I Shares.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

In the foregoing 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 an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for Class R Shares, which are not shown, will vary from those shown for Class I Shares. A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURN AS OF DECEMBER 31, 2012

Russell 2000 Growth Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

14.59%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

3.49%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

9.80%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

5.80%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 08, 1993

Alger SmallCap Growth Institutional Fund Class I

Risk/Return:

rr_RiskReturnAbstract

Shareholder Fees (fees paid directly from your investment)

rr_MaximumAccountFeeOverAssets

none

Management Fees

rr_ManagementFeesOverAssets

0.81%

^[1]

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses (including shareholder servicing fees of .25%)

rr_OtherExpensesOverAssets

0.42%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.23%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

125

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

390

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

676

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

1,489

Annual Return 2003

rr_AnnualReturn2003

41.88%

Annual Return 2004

rr_AnnualReturn2004

16.48%

Annual Return 2005

rr_AnnualReturn2005

15.79%

Annual Return 2006

rr_AnnualReturn2006

17.69%

Annual Return 2007

rr_AnnualReturn2007

15.52%

Annual Return 2008

rr_AnnualReturn2008

(45.91%)

Annual Return 2009

rr_AnnualReturn2009

43.71%

Annual Return 2010

rr_AnnualReturn2010

25.63%

Annual Return 2011

rr_AnnualReturn2011

(2.91%)

Annual Return 2012

rr_AnnualReturn2012

12.43%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

12.43%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

1.29%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

10.74%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

8.70%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 08, 1993

Alger SmallCap Growth Institutional Fund Class I | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

10.56%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.82%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

10.48%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

7.77%

Alger SmallCap Growth Institutional Fund Class I | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

10.58%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

1.09%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

9.62%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

7.39%

Alger SmallCap Growth Institutional Fund Class R

Risk/Return:

rr_RiskReturnAbstract

Shareholder Fees (fees paid directly from your investment)

rr_MaximumAccountFeeOverAssets

none

Management Fees

rr_ManagementFeesOverAssets

0.81%

^[1]

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.50%

Other Expenses (including shareholder servicing fees of .25%)

rr_OtherExpensesOverAssets

0.42%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.73%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

176

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

545

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

939

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,041

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

11.85%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

0.80%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

10.22%

^[2]

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

8.17%

^[2]

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 27, 2003

[1] The Fund and Fred Alger Management, Inc. have adopted fee breakpoints for Alger Small Cap Growth Institutional Fund. The management fee for assets in excess of $1 billion is .75%.

[2] Performance of the Fund's Class R Shares prior to January 27, 2003 reflects the performance of the Fund's Class I Shares, as adjusted with currently applicable operating expenses, which differ from historical charges and expenses.

XML

Document and Entity Information	0 Months Ended
	Oct. 31, 2013
Risk/Return:
Document Type	485BPOS
Document Period End Date	Oct. 31, 2013
Registrant Name	ALGER INSTITUTIONAL FUNDS
Central Index Key	0000911415
Amendment Flag	false
Document Creation Date	Feb. 22, 2013
Document Effective Date	Feb. 28, 2013
Prospectus Date	Mar. 01, 2013
Alger Capital Appreciation Institutional Fund | Alger Capital Appreciation Institutional Fund | Alger Capital Appreciation Institutional Fund Class I
Risk/Return:
Trading Symbol	ALARX
Alger Capital Appreciation Institutional Fund | Alger Capital Appreciation Institutional Fund | Alger Capital Appreciation Institutional Fund Class R
Risk/Return:
Trading Symbol	ACARX
Alger Capital Appreciation Focus Fund | Alger Capital Appreciation Focus Fund | Alger Capital Appreciation Focus Fund Class R
Risk/Return:
Trading Symbol	ALGIX
Alger Capital Appreciation Focus Fund | Alger Capital Appreciation Focus Fund | Alger Capital Appreciation Focus Fund Class Z
Risk/Return:
Trading Symbol	ALZFX
Alger Capital Appreciation Focus Fund | Alger Capital Appreciation Focus Fund | Alger Capital Appreciation Focus Fund Class I
Risk/Return:
Trading Symbol	ALGRX
Alger Capital Appreciation Focus Fund | Alger Capital Appreciation Focus Fund | Alger Capital Appreciation Focus Fund Class A
Risk/Return:
Trading Symbol	ALAFX
Alger Capital Appreciation Focus Fund | Alger Capital Appreciation Focus Fund | Alger Capital Appreciation Focus Fund Class C
Risk/Return:
Trading Symbol	ALCFX
Alger Mid Cap Growth Institutional Fund | Alger Mid Cap Growth Institutional Fund | Alger MidCap Growth Institutional Fund Class I
Risk/Return:
Trading Symbol	ALMRX
Alger Mid Cap Growth Institutional Fund | Alger Mid Cap Growth Institutional Fund | Alger MidCap Growth Institutional Fund Class R
Risk/Return:
Trading Symbol	AGIRX
Alger Small Cap Growth Institutional Fund | Alger Small Cap Growth Institutional Fund | Alger SmallCap Growth Institutional Fund Class I
Risk/Return:
Trading Symbol	ALSRX
Alger Small Cap Growth Institutional Fund | Alger Small Cap Growth Institutional Fund | Alger SmallCap Growth Institutional Fund Class R
Risk/Return:
Trading Symbol	ASIRX

XML

Alger Mid Cap Growth Institutional Fund | Alger Mid Cap Growth Institutional Fund

Alger Mid Cap Growth Institutional Fund

INVESTMENT OBJECTIVE

Alger Mid Cap Growth Institutional Fund seeks long-term capital appreciation.

FUND FEES AND EXPENSES

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. There are no sales charges on purchases or redemptions

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees Alger Mid Cap Growth Institutional Fund	Alger MidCap Growth Institutional Fund Class I	Alger MidCap Growth Institutional Fund Class R
Shareholder Fees (fees paid directly from your investment)	none	none

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

Annual Fund Operating Expenses Alger Mid Cap Growth Institutional Fund		Alger MidCap Growth Institutional Fund Class I	Alger MidCap Growth Institutional Fund Class R
Management Fees	[1]	0.76%	0.76%
Distribution (12b-1) Fees		none	0.50%
Other Expenses (including shareholder servicing fees of .25%)		0.47%	0.50%
Total Annual Fund Operating Expenses		1.23%	1.76%

EXAMPLE

The following 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 $10,000.00 in the Fund for the time periods indicated, that your investment has a 5% return each year and that the Fund's operating expenses remain the same.

Although your actual costs may be higher or lower, based on these assumptions you would pay the following expenses whether or not you redeemed your shares at the end of each period:

Expense Example Alger Mid Cap Growth Institutional Fund (USD $)	1 YEAR	3 YEARS	5 YEARS	10 YEARS
Alger MidCap Growth Institutional Fund Class I	125	390	676	1,489
Alger MidCap Growth Institutional Fund Class R	179	554	954	2,073

PORTFOLIO TURNOVER

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "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 232.99% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGY

Fred Alger Management, Inc. believes companies undergoing Positive Dynamic Change offer the best investment opportunities. Positive Dynamic Change refers to companies realizing High Unit Volume Growth or companies undergoing Positive Lifecycle Change. High Unit Volume Growth companies are traditional growth companies experiencing, for example, significantly growing demand or market dominance. Positive Lifecycle Change companies are, for example, companies benefitting from regulatory change, a new product introduction or management change.

The Fund focuses on mid-sized companies that Fred Alger Management, Inc. believes demonstrate promising growth potential. Under normal circumstances, the Fund invests at least 80% of its net assets in equity securities of companies that, at the time of purchase of the securities, have total market capitalization within the range of companies included in the Russell Midcap Growth Index or the S&P MidCap 400 Index, as reported by the indexes as of the most recent quarter-end. Both indexes are designed to track the performance of medium-capitalization stocks. At December 31, 2012, the market capitalization of the companies in these indexes ranged from $350 million to $25 billion.

The Fund can also invest in derivative instruments. The Fund currently expects that its primary uses of derivatives will involve: (1) purchasing put and call options and selling (writing) covered put and call options, on securities and securities indexes, to increase gain, to hedge against the risk of unfavorable price movements in the underlying securities, or to provide diversification of risk, and (2) entering into forward currency contracts to hedge the Fund's foreign currency exposure when it holds, or proposes to hold, non-U.S. dollar denominated securities.

PRINCIPAL RISKS

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing. The Fund's price per share will fluctuate due to changes in the market prices of its investments. Also, the Fund's investments may not grow as fast as the rate of inflation and stocks tend to be more volatile than some other investments you could make, such as bonds.

Prices of growth stocks tend to be higher in relation to their companies' earnings and may be more sensitive to market, political and economic developments than other stocks, making their prices more volatile. An investment in the Fund may be better suited to investors who seek long-term capital growth and can tolerate fluctuations in their investment's value.

A small investment in derivatives could have a potentially large impact on the Fund's performance. When purchasing options, the Fund bears the risk that if the market value of the underlying security does not move to a level that would make exercise of the option profitable, the option will expire unexercised. When a call option written by the Fund is exercised, the Fund will not participate in any increase in the underlying security's value above the exercise price. When a put option written by the Fund is exercised, the Fund will be required to purchase the underlying security at a price in excess of its market value. Use of options on securities indexes is subject to the risk that trading in the options may be interrupted if trading in certain securities included in the index is interrupted, the risk that price movements in the Fund's portfolio securities may not correlate precisely with movements in the level of an index, and the risk that Fred Alger Management, Inc. may not predict correctly movements in the direction of a particular market or of the stock market generally. Because certain options may require settlement in cash, the Fund may be forced to liquidate portfolio securities to meet settlement obligations. Forward currency contracts are subject to currency exchange rate risks and the risk of non-performance by the contract counterparty.

The following risks may also apply:

•  there may be greater risk in investing in medium-capitalization companies rather than larger, more established companies owing to such factors as inexperienced management and limited product lines or financial resources.

•  it may be difficult or impossible to liquidate a security position at a time and price acceptable to the Fund owing to the potentially less frequent trading of stocks of smaller market capitalization.

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

PERFORMANCE

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance. Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future. Updated performance information is available on the Fund's website www.alger.com.

ANNUAL TOTAL RETURN FOR CLASS I SHARES as of December 31 (%)

Best Quarter:
Q2 2003	20.09%
Worst Quarter:
Q4 2008	-32.88%

AVERAGE ANNUAL TOTAL RETURN AS OF DECEMBER 31, 2012

Average Annual Returns Alger Mid Cap Growth Institutional Fund	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years		Average Annual Returns, Since Inception		Average Annual Returns, Inception Date
Alger MidCap Growth Institutional Fund Class I	16.24%	(4.38%)	7.81%		11.33%		Nov. 08, 1993
Alger MidCap Growth Institutional Fund Class R	15.63%	(4.88%)	7.27%	[1]	10.78%	[1]	Jan. 27, 2003
After Taxes on Distributions Alger MidCap Growth Institutional Fund Class I	16.14%	(4.42%)	6.64%		8.73%
After Taxes on Distributions and Sale of Fund Shares Alger MidCap Growth Institutional Fund Class I	10.56%	(3.69%)	6.32%		8.57%
Russell MidCap Growth Index (reflects no deduction for fees, expenses or taxes)	15.81%	3.23%	10.32%		8.37%		Nov. 08, 1993

In the foregoing 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 an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for Class R Shares, which are not shown, will vary from those shown for Class I Shares. A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

[1] The Fund and Fred Alger Management, Inc. have adopted fee breakpoints for Alger Mid Cap Growth Institutional Fund. The management fee for assets in excess of $1 billion is .70%.

[1] Performance of the Fund's Class R Shares prior to January 27, 2003 reflects the performance of the Fund's Class I Shares, as adjusted with currently applicable operating expenses, which differ from historical charges and expenses.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Alger Capital Appreciation Focus Fund

Objective [Heading]

rr_ObjectiveHeading

INVESTMENT OBJECTIVE

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

Alger Capital Appreciation Focus Fund seeks long-term capital appreciation.

Expense [Heading]

rr_ExpenseHeading

FUND FEES AND EXPENSES

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. There are no sales charges on purchases or redemptions.

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 percentage of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

2014-02-28

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 (or "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 153.72% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

153.72%

Expenses Restated to Reflect Current [Text]

rr_ExpensesRestatedToReflectCurrent

The Annual Fund Operating Expenses are as of the fiscal year ended October 31, 2012, adjusted for fees currently in place.

Expense Example [Heading]

rr_ExpenseExampleHeading

EXAMPLE

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The following 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, that your investment has a 5% return each year and that the Fund's operating expenses remain the same.

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

Although your actual costs may be higher or lower, based on these assumptions you would pay the following expenses whether or not you redeemed your shares at the end of each period:

Strategy [Heading]

rr_StrategyHeading

PRINCIPAL INVESTMENT STRATEGY

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Fred Alger Management, Inc. believes companies undergoing Positive Dynamic Change offer the best investment opportunities. Positive Dynamic Change refers to companies realizing High Unit Volume Growth or companies undergoing Positive Lifecycle Change. High Unit Volume Growth companies are traditional growth companies experiencing, for example, significantly growing demand or market dominance. Positive Lifecycle Change companies are, for example, companies benefitting from regulatory change, a new product introduction or management change.

The Fund focuses on equity securities of companies of any capitalization that Fred Alger Management, Inc. believes demonstrate promising growth potential.

The Fund intends to invest a substantial portion of its assets in a small number of issuers, and may therefore concentrate its holdings in fewer business sectors or industries. Generally the Fund will hold less than 50 securities. The number of securities held by the Fund may occasionally exceed this range, including, but not limited to, when the portfolio manager is accumulating new positions, phasing out and replacing existing positions, or responding to unusual market conditions. In addition, the Fund will seek to have an annual portfolio turnover rate of less than 100%. From time to time, such as in situations described above, the portfolio turnover rate may exceed 100%.

The Fund can also invest in derivative instruments. The Fund currently expects that its primary use of derivatives will involve entering into forward currency contracts to hedge the Fund's foreign currency exposure when it holds, or proposes to hold, non-U.S. dollar denominated securities.

Risk [Heading]

rr_RiskHeading

PRINCIPAL RISKS

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing. The Fund's price per share will fluctuate due to changes in the market prices of its investments. Also, the Fund's investments may not grow as fast as the rate of inflation and stocks tend to be more volatile than some other investments you could make, such as bonds.

Prices of growth stocks tend to be higher in relation to their companies' earnings and may be more sensitive to market, political and economic developments than other stocks, making their prices more volatile. An investment in the Fund may be better suited to investors who seek long-term capital growth and can tolerate fluctuations in their investment's value.

A small investment in derivatives could have a potentially large impact on the Fund's performance. Forward currency contracts are subject to currency exchange rate risks and the risk of non-performance by the contract counterparty.

The following risks may also apply:

•  investing in companies of all capitalizations involves the risk that smaller issuers in which the Fund invests may have limited product lines or financial resources, or lack management depth.

•  it may be difficult or impossible to liquidate a security position at a time and price acceptable to the Fund because of the potentially less frequent trading of stocks of smaller market capitalization.

•  the Fund may have a more concentrated portfolio than other funds, so it may be more vulnerable to changes in the market value of a single issuer and may be more susceptible to risks associated with a single economic, political or regulatory occurrence than a fund that has a more diversified portfolio.

•  the Fund may have substantial holdings within a particular sector, and companies in similar industries may be similarly affected by particular economic or market events.

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

Risk Lose Money [Text]

rr_RiskLoseMoney

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

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

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

PERFORMANCE

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance. Prior to December 31, 2012, the Fund followed different investment strategies under the name "Alger Large Cap Growth Institutional Fund" and was managed by different portfolio managers. Performance prior to December 31, 2012 reflects those management styles and does not reflect the current investment personnel and strategies of the Fund. Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future. Updated performance information is available on the Fund's website www.alger.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.alger.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

ANNUAL TOTAL RETURN FOR CLASS I SHARES as of December 31 (%)

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter:
Q2 2003	17.17%
Worst Quarter:
Q4 2008	-28.17%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter:

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2003

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

17.17%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter:

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(28.17%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

In the foregoing 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.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for Class R Shares, which are not shown, will vary from those shown for Class I Shares.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

In the foregoing 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 an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for Class R Shares, which are not shown, will vary from those shown for Class I Shares. A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

Caption

rr_AverageAnnualReturnCaption

AVERAGE ANNUAL TOTAL RETURN AS OF DECEMBER 31, 2012

Russell 1000 Growth Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

15.26%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

3.12%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

7.52%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

7.42%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 08, 1993

Alger Capital Appreciation Focus Fund Class I

Risk/Return:

rr_RiskReturnAbstract

Shareholder Fees (fees paid directly from your investment)

rr_MaximumAccountFeeOverAssets

none

Management Fees

rr_ManagementFeesOverAssets

0.71%

^[1],[2]

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

^[1]

Other Expenses (including shareholder servicing fees of .25%)

rr_OtherExpensesOverAssets

1.12%

^[1]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.83%

^[1]

Fee Waiver or Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

(0.68%)

^[1],[3]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_NetExpensesOverAssets

1.15%

^[1]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

117

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

509

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

927

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,092

Annual Return 2003

rr_AnnualReturn2003

34.37%

Annual Return 2004

rr_AnnualReturn2004

4.80%

Annual Return 2005

rr_AnnualReturn2005

11.70%

Annual Return 2006

rr_AnnualReturn2006

4.64%

Annual Return 2007

rr_AnnualReturn2007

18.84%

Annual Return 2008

rr_AnnualReturn2008

(47.25%)

Annual Return 2009

rr_AnnualReturn2009

40.43%

Annual Return 2010

rr_AnnualReturn2010

13.80%

Annual Return 2011

rr_AnnualReturn2011

(0.73%)

Annual Return 2012

rr_AnnualReturn2012

8.73%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

8.73%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(1.87%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

5.93%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

6.95%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 08, 1993

Alger Capital Appreciation Focus Fund Class I | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

8.73%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(1.95%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

5.88%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

5.57%

Alger Capital Appreciation Focus Fund Class I | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

5.67%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(1.63%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

5.18%

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

5.36%

Alger Capital Appreciation Focus Fund Class R

Risk/Return:

rr_RiskReturnAbstract

Shareholder Fees (fees paid directly from your investment)

rr_MaximumAccountFeeOverAssets

none

Management Fees

rr_ManagementFeesOverAssets

0.71%

^[1],[2]

Distribution (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.50%

^[1]

Other Expenses (including shareholder servicing fees of .25%)

rr_OtherExpensesOverAssets

1.32%

^[1]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.53%

^[1]

Fee Waiver or Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

^[1],[3]

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_NetExpensesOverAssets

2.53%

^[1]

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

256

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

788

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,345

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,866

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

7.98%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

(2.48%)

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

5.34%

^[4]

Average Annual Returns, Since Inception

rr_AverageAnnualReturnSinceInception

6.38%

^[4]

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 27, 2003

[1] The Annual Fund Operating Expenses are as of the fiscal year ended October 31, 2012, adjusted for fees currently in place.

[2] The Fund and Fred Alger Management, Inc. have adopted fee breakpoints for Alger Capital Appreciation Focus Fund. The management fee for assets over $1 billion is .60%.

[3] Fred Alger Management, Inc. has contractually agreed to reimburse Fund expenses (excluding interest, taxes, brokerage, and extraordinary expenses) through February 28, 2014 to the extent necessary to limit the total annual fund operating expenses of the Class I Shares of the Fund to 1.15% of the class's average daily net assets. This expense reimbursement cannot be terminated.

[4] Performance of the Fund's Class R Shares prior to January 27, 2003 reflects the performance of the Fund's Class I Shares, as adjusted with currently applicable operating expenses, which differ from historical charges and expenses.

XML

Alger Capital Appreciation Focus Fund | Alger Capital Appreciation Focus Fund

Alger Capital Appreciation Focus Fund

INVESTMENT OBJECTIVE

Alger Capital Appreciation Focus Fund seeks long-term capital appreciation.

FUND FEES AND EXPENSES

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. There are no sales charges on purchases or redemptions. "Other Expenses" below are estimated assuming $1 million in net assets. If actual net assets are less, the actual expense ratio will be higher.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	Alger Capital Appreciation Focus Fund Alger Capital Appreciation Focus Fund Class Z
Shareholder Fees (fees paid directly from your investment)	none

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

Annual Fund Operating Expenses		Alger Capital Appreciation Focus Fund Alger Capital Appreciation Focus Fund Class Z
Management Fees	[1]	0.71%
Distribution and/or Service (12b-1) Fees		none
Other Expenses		2.22%
Total Annual Fund Operating Expenses		2.93%
Expense Reimbursement	[2]	2.04%
Total Annual Fund Operating Expenses After Expense Reimbursement		0.89%

EXAMPLE

The following 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, that your investment has a 5% return each year and that the Fund's operating expenses remain the same.

Although your actual costs may be higher or lower, based on these assumptions you would pay the following expenses regardless of whether you redeemed your shares at the end of each period:

Expense Example (USD $)	1 YEAR	3 YEARS	5 YEARS	10 YEARS
Alger Capital Appreciation Focus Fund Alger Capital Appreciation Focus Fund Class Z	91	714	1,362	3,106

PORTFOLIO TURNOVER

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "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 examples, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 153.72% of the average value of its portfolio.

PRINCIPAL INVESTMENT STRATEGY

Fred Alger Management, Inc. believes companies undergoing Positive Dynamic Change offer the best investment opportunities. Positive Dynamic Change refers to companies realizing High Unit Volume Growth or companies undergoing Positive Lifecycle Change. High Unit Volume Growth Companies are traditional growth companies experiencing, for example, significantly growing demand or market dominance. Positive Lifecycle Change companies are, for example, companies benefiting from regulatory change, a new product introduction or management change.

The Fund focuses on equity securities of companies of any capitalization that Fred Alger Management, Inc. believes demonstrate promising growth potential.

The Fund intends to invest a substantial portion of its assets in a small number of issuers, and may therefore concentrate its holdings in fewer business sectors or industries. Generally the Fund will hold less than 50 securities. The number of securities held by the Fund may occasionally exceed this range, including, but not limited to, when the portfolio manager is accumulating new positions, phasing out and replacing existing positions, or responding to unusual market conditions. In addition, the Fund will seek to have an annual portfolio turnover rate of less than 100%. From time to time, such as in situations described above, the portfolio turnover rate may exceed 100%.

The Fund can also invest in derivative instruments. The Fund currently expects that its primary use of derivatives will involve entering into forward currency contract to hedge the Fund's foreign currency exposure when it holds, or proposes to hold, non-U.S. dollar denominated securities.

PRINCIPAL RISKS

As with any fund that invests in stocks, your investment will fluctuate in value, and the loss of your investment is a risk of investing. The Fund's price per share will fluctuate due to changes in the market prices of its investments. Also, the Fund's investments may not grow as fast as the rate of inflation and stocks tend to be more volatile than some other investments you could make, such as bonds.

Prices of growth stocks tend to be higher in relation to their companies' earnings and may be more sensitive to market, political and economic developments than other stocks, making their prices more volatile. An investment in the Fund may be better suited to investors who seek long-term capital growth and can tolerate fluctuations in their investment's value.

A small investment in derivatives could have a potentially large impact on the Fund's performance. Forward currency contracts are subject to currency exchange rate risks and the risk of non-performance by the contract counterparty.

The following risks may also apply:

•  investing in companies of all capitalizations involves the risk that smaller issuers in which the Fund invests may have limited product lines or financial resources, or lack management depth.

•  it may be difficult or impossible to liquidate a security position at a time and price acceptable to the Fund because of the potentially less frequent trading of stocks of smaller market capitalization.

•  the Fund may have a more concentrated portfolio than other funds, so it may be more vulnerable to changes in the market value of a single issuer and may be more susceptible to risks associated with a single economic, political or regulatory occurrence than a fund that has a more diversified portfolio.

•  the Fund may have substantial holdings within a particular sector, and companies in similar industries may be similarly affected by particular economic or market events.

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

PERFORMANCE

The following bar chart and the table beneath it provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual returns for the indicated periods compare with those of an appropriate benchmark of market performance. Class Z Shares were not offered prior to December 31, 2012. Historical performance prior to December 31, 2012 is that of the Fund's Class I Shares. Previously, the Fund followed different investment strategies under the name "Alger Large Cap Growth Institutional Fund" and was managed by different portfolio managers. Performance prior to December 31, 2012 reflects those management styles and does not reflect the current investment personnel and strategies of the Fund. Remember that the Fund's past performance (before and after taxes) is not necessarily an indication of how it will perform in the future. Updated performance information is available on the Fund's website www.alger.com.

ANNUAL TOTAL RETURN FOR CLASS I SHARES as of December 31 (%)

Best Quarter:
Q2 2003	17.17%
Worst Quarter:
Q4 2008	-28.17%

AVERAGE ANNUAL TOTAL RETURN AS OF DECEMBER 31, 2012

Average Annual Returns Alger Capital Appreciation Focus Fund	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years	Average Annual Returns, Since Inception	Average Annual Returns, Inception Date
Alger Capital Appreciation Focus Fund Class Z	8.73%	(1.87%)	5.93%	6.95%	Nov. 08, 1993
After Taxes on Distributions Alger Capital Appreciation Focus Fund Class Z	8.73%	(1.95%)	5.88%	5.57%
After Taxes on Distributions and Sale of Fund Shares Alger Capital Appreciation Focus Fund Class Z	5.67%	(1.63%)	5.18%	5.36%
Russell 1000 Growth Index (reflects no deduction for fees, expenses or taxes)	15.26%	3.12%	7.52%	7.42%	Nov. 08, 1993

In the foregoing 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 an investor's tax situation and may differ from those shown. The after-tax returns shown may not be relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. A "return after taxes on distributions and sale of fund shares" may sometimes be higher than the other two return figures; this happens where there is a capital loss on redemptions, giving rise to a tax benefit to the shareholder.

[1] The Fund and Fred Alger Management, Inc. have adopted fee breakpoints for Alger Capital Appreciation Focus Fund. The management fee for assets in excess of $1 billion is .60%.

[2] Fred Alger Management, Inc. has contractually agreed to reimburse Fund expenses (excluding interest, taxes, brokerage, and extraordinary expenses) through February 28, 2014 to the extent necessary to limit the total annual fund operating expenses of the Class Z Shares of the Fund to .89% of the class's average daily net assets. This expense reimbursement cannot be terminated.