485BPOS

As filed with the Securities and Exchange Commission on February 15, 2013

Securities Act File No. 33-26305

Investment Company Act File No. 811-05742

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933	x
Pre-Effective Amendment No.	¨
Post-Effective Amendment No. 273	x
and/or
REGISTRATION STATEMENT
UNDER
THE INVESTMENT COMPANY ACT OF 1940	x
Amendment No. 275	x

(Check appropriate box or boxes)

BLACKROCK FUNDS^SM

(Exact Name of Registrant as Specified in Charter)

100 Bellevue Parkway

Wilmington, Delaware 19809

(Address of Principal Executive Office)

Registrant’s Telephone Number, including Area Code (800) 441-7762

John M. Perlowski

BlackRock Funds^SM

55 East 52^nd Street

New York, New York 10055

United States of America

(Name and Address of Agent for Service)

Copies to:

Frank P. Bruno, Esq.	Benjamin Archibald, Esq.
Sidley Austin LLP	BlackRock Advisors, LLC
787 Seventh Avenue	55 East 52nd Street
New York, New York 10019-6018	New York, New York 10055

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

x Immediately upon filing pursuant to paragraph (b)

¨ On (date) pursuant to paragraph (b)

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

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

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

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

If appropriate, check the following box:

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

Title of Securities Being Registered: Shares of beneficial interest, par value $.001 per share.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all the requirements for effectiveness of this Post-Effective Amendment to its Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this Post-Effective Amendment to its Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of New York and the State of New York, on February 15, 2013.

BLACKROCK FUNDSSM
ON BEHALF OF BLACKROCK MID-CAP GROWTH EQUITY PORTFOLIO AND BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO
(REGISTRANT)
By:	/s/ John M. Perlowski
	John M. Perlowski
	President and Chief Executive Officer

Pursuant to the requirements of the Securities Act of 1933, this Post-Effective Amendment to its Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

Signature	Title	Date
/s/ John M. Perlowski	President and Chief Executive Officer (Principal Executive Officer)	February 15, 2013
John M. Perlowski
/s/ Neal J. Andrews	Chief Financial Officer (Principal Financial and Accounting Officer)	February 15, 2013
Neal J. Andrews
DAVID O. BEIM*	Trustee
David O. Beim
RONALD W. FORBES*	Trustee
Ronald W. Forbes
DR. MATINA S. HORNER*	Trustee
Dr. Matina S. Horner
RODNEY D. JOHNSON*	Trustee
Rodney D. Johnson
HERBERT I. LONDON*	Trustee
Herbert I. London
IAN A. MACKINNON*	Trustee
Ian A. MacKinnon
CYNTHIA A. MONTGOMERY*	Trustee
Cynthia A. Montgomery
JOSEPH P. PLATT*	Trustee
Joseph P. Platt

ROBERT C. ROBB, JR.*	Trustee
Robert C. Robb, Jr.
TOBY ROSENBLATT*	Trustee
Toby Rosenblatt
KENNETH L. URISH*	Trustee
Kenneth L. Urish
FREDERICK W. WINTER*	Trustee
Frederick W. Winter
PAUL L. AUDET*	Trustee
Paul L. Audet
HENRY GABBAY*	Trustee
Henry Gabbay

*By:	/s/ Benjamin Archibald	February 15, 2013
	Benjamin Archibald (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

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Jan. 28, 2013
Investor, Institutional and R Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Overview Key Facts About BlackRock Mid-Cap Growth Equity Portfolio
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of BlackRock Mid-Cap Growth Equity Portfolio (“Mid-Cap Growth Equity” or the “Fund”), a series of BlackRock FundsSM (the “Trust”), is long-term capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of Mid-Cap Growth Equity. 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 the fund complex advised by BlackRock Advisors, LLC (“BlackRock”). More information about these and other discounts is available from your financial professional and in the “Details About the Share Classes” section on page 21 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-58 of the Fund’s statement of additional information.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	February 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when 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 88% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	88.00%
Expenses Deferred Charges [Text Block]	rr_ExpensesDeferredChargesTextBlock	A contingent deferred sales charge (“CDSC”) of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.
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 the fund complex advised by BlackRock Advisors, LLC (“BlackRock”).
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	25,000
Expense Example [Heading]	rr_ExpenseExampleHeading	Example:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes 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 your costs would be:
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 Strategies of the Fund
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Mid-Cap Growth Equity normally invests at least 80% of its net assets in equity securities issued by U.S. mid-capitalization companies which Fund management believes have above-average earnings growth potential. Equity securities consist primarily of common stock, preferred stock, securities convertible into common stock and securities or other instruments whose price is linked to the value of common stock. Although a universal definition of mid-capitalization companies does not exist, the Fund generally defines these companies, at the time of the Fund’s investment, as those with market capitalizations comparable in size to the companies in the Russell Midcap® Growth Index (between approximately $1.275 billion and $19.075 billion as of June 30, 2012, the most recent rebalance date). In the future, the Fund may define mid-capitalization companies using a different index or classification system. The Fund seeks to buy primarily common stock but also can invest in preferred stock, convertible securities and other equity securities. From time to time the Fund may invest in shares of companies through “new issues” or initial public offerings (“IPOs”). The Fund may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities (commonly known as derivatives). The primary purpose of using derivatives is to attempt to reduce risk to the Fund as a whole (hedge), but they may also be used to maintain liquidity and commit cash pending investment. Fund management also may, but under normal market conditions generally does not intend to, use derivatives for speculation to increase returns.
Risk [Heading]	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Risk is inherent in all investing. The value of your investment in Mid-Cap Growth Equity, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund. Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock. Derivatives Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives. Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions. Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles. Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage. Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money. Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies. “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The information shows you how Mid-Cap Growth Equity’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Russell Midcap® Growth Index. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information shows you how Mid-Cap Growth Equity’s performance has varied year by year and provides some indication of the risks of investing in the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	(800) 882-0052
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://www.blackrock.com/funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	As with all such investments, past performance (before and after taxes) is not an indication of future results.
Bar Chart [Heading]	rr_BarChartHeading	Investor A Shares ANNUAL TOTAL RETURNS BlackRock Mid-Cap Growth Equity Portfolio As of 12/31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the ten-year period shown in the bar chart, the highest return for a quarter was 20.97% (quarter ended June 30, 2009) and the lowest return for a quarter was –28.87% (quarter ended December 31, 2008).
Performance Table Heading	rr_PerformanceTableHeading	As of 12/31/12 Average Annual Total Returns
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	However, the table includes all applicable fees and sales charges.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their 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 are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C, Institutional and Class R Shares will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C, Institutional and Class R Shares will vary.
Investor, Institutional and R Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.25%
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none	[1]
Management Fee	rr_ManagementFeesOverAssets	0.80%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.50%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.55%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.16%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.39%	[2]
1 Year	rr_ExpenseExampleYear01	659
3 Years	rr_ExpenseExampleYear03	974
5 Years	rr_ExpenseExampleYear05	1,311
10 Years	rr_ExpenseExampleYear10	2,261
2003	rr_AnnualReturn2003	33.50%
2004	rr_AnnualReturn2004	15.11%
2005	rr_AnnualReturn2005	10.21%
2006	rr_AnnualReturn2006	5.98%
2007	rr_AnnualReturn2007	19.29%
2008	rr_AnnualReturn2008	(46.37%)
2009	rr_AnnualReturn2009	48.82%	[3]
2010	rr_AnnualReturn2010	15.02%
2011	rr_AnnualReturn2011	(3.35%)
2012	rr_AnnualReturn2012	10.67%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	20.97%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(28.87%)
1 Year	rr_AverageAnnualReturnYear01	4.89%
5 Years	rr_AverageAnnualReturnYear05	(1.43%)	[3]
10 Years	rr_AverageAnnualReturnYear10	7.14%	[3]
Investor, Institutional and R Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO | Investor B Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	4.50%	[4]
Management Fee	rr_ManagementFeesOverAssets	0.80%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.79%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.59%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.43%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	2.16%	[2]
1 Year	rr_ExpenseExampleYear01	669
3 Years	rr_ExpenseExampleYear03	1,115
5 Years	rr_ExpenseExampleYear05	1,537
10 Years	rr_ExpenseExampleYear10	2,638
1 Year	rr_ExpenseExampleNoRedemptionYear01	219
3 Years	rr_ExpenseExampleNoRedemptionYear03	765
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,337
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,638
1 Year	rr_AverageAnnualReturnYear01	5.27%
5 Years	rr_AverageAnnualReturnYear05	(1.53%)	[3]
10 Years	rr_AverageAnnualReturnYear10	7.05%	[3]
Investor, Institutional and R Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO | Investor C Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[5]
Management Fee	rr_ManagementFeesOverAssets	0.80%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.51%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.31%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.15%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	2.16%	[2]
1 Year	rr_ExpenseExampleYear01	319
3 Years	rr_ExpenseExampleYear03	707
5 Years	rr_ExpenseExampleYear05	1,222
10 Years	rr_ExpenseExampleYear10	2,634
1 Year	rr_ExpenseExampleNoRedemptionYear01	219
3 Years	rr_ExpenseExampleNoRedemptionYear03	707
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,222
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,634
1 Year	rr_AverageAnnualReturnYear01	8.77%
5 Years	rr_AverageAnnualReturnYear05	(1.13%)	[3]
10 Years	rr_AverageAnnualReturnYear10	6.89%	[3]
Investor, Institutional and R Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO | Institutional Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Management Fee	rr_ManagementFeesOverAssets	0.80%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.31%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.11%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.11%	[2]
1 Year	rr_ExpenseExampleYear01	113
3 Years	rr_ExpenseExampleYear03	353
5 Years	rr_ExpenseExampleYear05	612
10 Years	rr_ExpenseExampleYear10	1,352
1 Year	rr_AverageAnnualReturnYear01	10.96%
5 Years	rr_AverageAnnualReturnYear05	0.03%	[3]
10 Years	rr_AverageAnnualReturnYear10	8.17%	[3]
Investor, Institutional and R Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO | Class R Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Management Fee	rr_ManagementFeesOverAssets	0.80%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	0.54%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.84%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.19%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.65%	[2]
1 Year	rr_ExpenseExampleYear01	168
3 Years	rr_ExpenseExampleYear03	560
5 Years	rr_ExpenseExampleYear05	978
10 Years	rr_ExpenseExampleYear10	2,143
1 Year	rr_AverageAnnualReturnYear01	10.34%
5 Years	rr_AverageAnnualReturnYear05	(0.48%)	[3]
10 Years	rr_AverageAnnualReturnYear10	7.61%	[3]
Investor, Institutional and R Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO | Return After Taxes on Distributions | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	4.89%
5 Years	rr_AverageAnnualReturnYear05	(1.43%)	[3]
10 Years	rr_AverageAnnualReturnYear10	7.12%	[3]
Investor, Institutional and R Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO | Return After Taxes on Distributions and Sale of Shares | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	3.18%
5 Years	rr_AverageAnnualReturnYear05	(1.21%)	[3]
10 Years	rr_AverageAnnualReturnYear10	6.31%	[3]
Investor, Institutional and R Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO | Russell Midcap® Growth Index (Reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	15.81%
5 Years	rr_AverageAnnualReturnYear05	3.23%	[3]
10 Years	rr_AverageAnnualReturnYear10	10.32%	[3]

[1] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[2] As described in the "Management of the Funds" section of the Fund's prospectus on pages 36-41, BlackRock has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) as a percentage of average daily net assets to 1.39% (for Investor A Shares), 2.16% (for Investor B and Investor C Shares), 1.11% (for Institutional Shares) and 1.65% (for Class R Shares) until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[3] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in settlement of litigation.

[4] The CDSC is 4.50% if shares are redeemed in less than one year. The CDSC for Investor B Shares decreases for redemptions made in subsequent years. After six years there is no CDSC on Investor B Shares. (See the section "Details About the Share Classes - Investor B Shares" in the Fund's prospectus for the complete schedule of CDSCs.)

[5] There is no CDSC on Investor C Shares after one year.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Jan. 28, 2013
Service Shares | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Overview Key Facts About BlackRock Small Cap Growth Equity Portfolio
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of BlackRock Small Cap Growth Equity Portfolio (“Small Cap Growth Equity” or the “Fund”), a series of BlackRock FundsSM (the “Trust”), is long-term capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Service Shares of Small Cap Growth Equity.
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	February 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when 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 147% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	147.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes 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 your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Small Cap Growth Equity normally invests at least 80% of its net assets in equity securities issued by U.S. small capitalization companies which Fund management believes offer superior prospects for growth. Equity securities consist primarily of common stock, preferred stock, securities convertible into common stock and securities or other instruments whose price is linked to the value of common stock. The Fund management team focuses on U.S. small capitalization emerging growth companies. Although a universal definition of small-capitalization companies does not exist, the Fund generally defines these companies, at the time of the Fund’s investment, as those with market capitalizations comparable in size to the companies in the Russell 2000® Growth Index (between approximately $53 million and $3.771 billion as of June 30, 2012, the most recent rebalance date). In the future, the Fund may define small-capitalization companies using a different index or classification system. The Fund seeks to buy primarily common stock but also can invest in preferred stock, convertible securities and other equity securities. From time to time the Fund may invest in shares of companies through “new issues” or initial public offerings (“IPOs”).
Risk [Heading]	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Risk is inherent in all investing. The value of your investment in Small Cap Growth Equity, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund. Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock. Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions. Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles. Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money. “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering. Small Cap and Emerging Growth Securities Risk — Small cap or emerging growth companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The information shows you how Small Cap Growth Equity’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Russell 2000® Growth Index. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information shows you how Small Cap Growth Equity’s performance has varied year by year and provides some indication of the risks of investing in the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	(800) 882-0052
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://www.blackrock.com/funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	As with all such investments, past performance (before and after taxes) is not an indication of future results.
Bar Chart [Heading]	rr_BarChartHeading	Service Shares ANNUAL TOTAL RETURNS BlackRock Small Cap Growth Equity Portfolio As of 12/31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the ten-year period shown in the bar chart, the highest return for a quarter was 26.06% (quarter ended June 30, 2009) and the lowest return for a quarter was –28.81% (quarter ended December 31, 2008).
Performance Table Heading	rr_PerformanceTableHeading	As of 12/31/12 Average Annual Total Returns
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	However, the table includes all applicable fees and sales charges.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Service Shares | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO | Service Shares
Risk/Return:	rr_RiskReturnAbstract
Management Fee	rr_ManagementFeesOverAssets	0.54%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.41%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.20%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[1]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.20%	[1]
1 Year	rr_ExpenseExampleYear01	122
3 Years	rr_ExpenseExampleYear03	381
5 Years	rr_ExpenseExampleYear05	660
10 Years	rr_ExpenseExampleYear10	1,455
2003	rr_AnnualReturn2003	54.86%
2004	rr_AnnualReturn2004	10.11%
2005	rr_AnnualReturn2005	6.14%
2006	rr_AnnualReturn2006	18.80%
2007	rr_AnnualReturn2007	15.07%
2008	rr_AnnualReturn2008	(40.03%)
2009	rr_AnnualReturn2009	34.43%
2010	rr_AnnualReturn2010	22.74%	[2]
2011	rr_AnnualReturn2011	(0.08%)
2012	rr_AnnualReturn2012	10.64%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	26.06%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(28.81%)
1 Year	rr_AverageAnnualReturnYear01	10.64%
5 Years	rr_AverageAnnualReturnYear05	1.81%	[2]
10 Years	rr_AverageAnnualReturnYear10	10.47%	[2]
Service Shares | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO | Return After Taxes on Distributions | Service Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	8.01%
5 Years	rr_AverageAnnualReturnYear05	1.24%	[2]
10 Years	rr_AverageAnnualReturnYear10	10.16%	[2]
Service Shares | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO | Return After Taxes on Distributions and Sale of Shares | Service Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	8.48%
5 Years	rr_AverageAnnualReturnYear05	1.39%	[2]
10 Years	rr_AverageAnnualReturnYear10	9.28%	[2]
Service Shares | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO | Russell 2000® Growth Index (Reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	14.59%
5 Years	rr_AverageAnnualReturnYear05	3.49%	[2]
10 Years	rr_AverageAnnualReturnYear10	9.80%	[2]

[1] As described in the "Management of the Funds" section of the Fund's prospectus on pages 25-30, BlackRock Advisors, LLC ("BlackRock") has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 1.29% of average daily net assets until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[2] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2010 in settlement of litigation.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Jan. 28, 2013
Document Creation Date	dei_DocumentCreationDate	Jan. 28, 2013

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Investor, Institutional and R Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO

Fund Overview

Key Facts About BlackRock Mid-Cap Growth Equity Portfolio

Investment Objective

The investment objective of BlackRock Mid-Cap Growth Equity Portfolio (“Mid-Cap Growth Equity” or the “Fund”), a series of BlackRock Funds^SM (the “Trust”), is long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of Mid-Cap Growth Equity. 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 the fund complex advised by BlackRock Advisors, LLC (“BlackRock”). More information about these and other discounts is available from your financial professional and in the “Details About the Share Classes” section on page 21 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-58 of the Fund’s statement of additional information.

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Investor, Institutional and R Shares BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO	Investor A Shares		Investor B Shares		Investor C Shares		Institutional Shares	Class R Shares
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	5.25%		none		none		none	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	none	[1]	4.50%	[2]	1.00%	[3]	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 Investor, Institutional and R Shares BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO		Investor A Shares	Investor B Shares	Investor C Shares	Institutional Shares	Class R Shares
Management Fee		0.80%	0.80%	0.80%	0.80%	0.80%
Distribution and/or Service (12b-1) Fees		0.25%	1.00%	1.00%	none	0.50%
Other Expenses		0.50%	0.79%	0.51%	0.31%	0.54%
Total Annual Fund Operating Expenses		1.55%	2.59%	2.31%	1.11%	1.84%
Fee Waivers and/or Expense Reimbursements	[1]	(0.16%)	(0.43%)	(0.15%)		(0.19%)
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	[1]	1.39%	2.16%	2.16%	1.11%	1.65%

Example:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes 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 your costs would be:

Expense Example Investor, Institutional and R Shares BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO (USD $)	1 Year	3 Years	5 Years	10 Years
Investor A Shares	659	974	1,311	2,261
Investor B Shares	669	1,115	1,537	2,638
Investor C Shares	319	707	1,222	2,634
Institutional Shares	113	353	612	1,352
Class R Shares	168	560	978	2,143

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

Expense Example, No Redemption Investor, Institutional and R Shares BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO (USD $)	1 Year	3 Years	5 Years	10 Years
Investor B Shares	219	765	1,337	2,638
Investor C Shares	219	707	1,222	2,634

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 may indicate higher transaction costs and may result in higher taxes when 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 88% of the average value of its portfolio.

Principal Investment Strategies of the Fund

Mid-Cap Growth Equity normally invests at least 80% of its net assets in equity securities issued by U.S. mid-capitalization companies which Fund management believes have above-average earnings growth potential. Equity securities consist primarily of common stock, preferred stock, securities convertible into common stock and securities or other instruments whose price is linked to the value of common stock. Although a universal definition of mid-capitalization companies does not exist, the Fund generally defines these companies, at the time of the Fund’s investment, as those with market capitalizations comparable in size to the companies in the Russell Midcap^® Growth Index (between approximately $1.275 billion and $19.075 billion as of June 30, 2012, the most recent rebalance date). In the future, the Fund may define mid-capitalization companies using a different index or classification system. The Fund seeks to buy primarily common stock but also can invest in preferred stock, convertible securities and other equity securities. From time to time the Fund may invest in shares of companies through “new issues” or initial public offerings (“IPOs”).

The Fund may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities (commonly known as derivatives). The primary purpose of using derivatives is to attempt to reduce risk to the Fund as a whole (hedge), but they may also be used to maintain liquidity and commit cash pending investment. Fund management also may, but under normal market conditions generally does not intend to, use derivatives for speculation to increase returns.

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in Mid-Cap Growth Equity, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund.

• Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock.

• Derivatives Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives.

• Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions.

• Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles.

• Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage.

• Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money.

• Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies.

• “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering.

Performance Information

The information shows you how Mid-Cap Growth Equity’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Russell Midcap^® Growth Index. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.

Investor A Shares
ANNUAL TOTAL RETURNS
BlackRock Mid-Cap Growth Equity Portfolio
As of 12/31

During the ten-year period shown in the bar chart, the highest return for a quarter was 20.97% (quarter ended June 30, 2009) and the lowest return for a quarter was –28.87% (quarter ended December 31, 2008).

As of 12/31/12
Average Annual Total Returns

Average Annual Total Returns Investor, Institutional and R Shares BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO	1 Year	5 Years		10 Years
Investor A	4.89%	(1.43%)	[1]	7.14%	[1]
Investor A Return After Taxes on Distributions	4.89%	(1.43%)	[1]	7.12%	[1]
Investor A Return After Taxes on Distributions and Sale of Shares	3.18%	(1.21%)	[1]	6.31%	[1]
Investor B	5.27%	(1.53%)	[1]	7.05%	[1]
Investor C	8.77%	(1.13%)	[1]	6.89%	[1]
Institutional	10.96%	0.03%	[1]	8.17%	[1]
Class R	10.34%	(0.48%)	[1]	7.61%	[1]
Russell Midcap® Growth Index (Reflects no deduction for fees, expenses or taxes)	15.81%	3.23%	[1]	10.32%	[1]

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 the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C, Institutional and Class R Shares will vary.

[1] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[2] The CDSC is 4.50% if shares are redeemed in less than one year. The CDSC for Investor B Shares decreases for redemptions made in subsequent years. After six years there is no CDSC on Investor B Shares. (See the section "Details About the Share Classes - Investor B Shares" in the Fund's prospectus for the complete schedule of CDSCs.)

[3] There is no CDSC on Investor C Shares after one year.

[1] As described in the "Management of the Funds" section of the Fund's prospectus on pages 36-41, BlackRock has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) as a percentage of average daily net assets to 1.39% (for Investor A Shares), 2.16% (for Investor B and Investor C Shares), 1.11% (for Institutional Shares) and 1.65% (for Class R Shares) until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[1] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in settlement of litigation.

[1] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in settlement of litigation.

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Service Shares | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO

Fund Overview

Key Facts About BlackRock Small Cap Growth Equity Portfolio

Investment Objective

The investment objective of BlackRock Small Cap Growth Equity Portfolio (“Small Cap Growth Equity” or the “Fund”), a series of BlackRock Funds^SM (the “Trust”), is long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold Service Shares of Small Cap Growth Equity.

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

Annual Fund Operating Expenses		Service Shares BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO
Management Fee		0.54%
Distribution and/or Service (12b-1) Fees		0.25%
Other Expenses		0.41%
Total Annual Fund Operating Expenses		1.20%
Fee Waivers and/or Expense Reimbursements	[1]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	[1]	1.20%

Example:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes 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 your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Service Shares BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO	122	381	660	1,455

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 may indicate higher transaction costs and may result in higher taxes when 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 147% of the average value of its portfolio.

Principal Investment Strategies of the Fund

Small Cap Growth Equity normally invests at least 80% of its net assets in equity securities issued by U.S. small capitalization companies which Fund management believes offer superior prospects for growth. Equity securities consist primarily of common stock, preferred stock, securities convertible into common stock and securities or other instruments whose price is linked to the value of common stock. The Fund management team focuses on U.S. small capitalization emerging growth companies. Although a universal definition of small-capitalization companies does not exist, the Fund generally defines these companies, at the time of the Fund’s investment, as those with market capitalizations comparable in size to the companies in the Russell 2000^® Growth Index (between approximately $53 million and $3.771 billion as of June 30, 2012, the most recent rebalance date). In the future, the Fund may define small-capitalization companies using a different index or classification system. The Fund seeks to buy primarily common stock but also can invest in preferred stock, convertible securities and other equity securities. From time to time the Fund may invest in shares of companies through “new issues” or initial public offerings (“IPOs”).

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in Small Cap Growth Equity, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund.

• Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock.

• Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions.

• Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles.

• Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money.

• “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering.

• Small Cap and Emerging Growth Securities Risk — Small cap or emerging growth companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.

Performance Information

The information shows you how Small Cap Growth Equity’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Russell 2000^® Growth Index. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.

Service Shares
ANNUAL TOTAL RETURNS
BlackRock Small Cap Growth Equity Portfolio
As of 12/31

During the ten-year period shown in the bar chart, the highest return for a quarter was 26.06% (quarter ended June 30, 2009) and the lowest return for a quarter was –28.81% (quarter ended December 31, 2008).

As of 12/31/12
Average Annual Total Returns

Average Annual Total Returns Service Shares	1 Year	5 Years		10 Years
BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO	10.64%	1.81%	[1]	10.47%	[1]
BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO Return After Taxes on Distributions	8.01%	1.24%	[1]	10.16%	[1]
BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO Return After Taxes on Distributions and Sale of Shares	8.48%	1.39%	[1]	9.28%	[1]
BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO Russell 2000® Growth Index (Reflects no deduction for fees, expenses or taxes)	14.59%	3.49%	[1]	9.80%	[1]

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 the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

[1] As described in the "Management of the Funds" section of the Fund's prospectus on pages 25-30, BlackRock Advisors, LLC ("BlackRock") has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 1.29% of average daily net assets until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[1] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2010 in settlement of litigation.

[1] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2010 in settlement of litigation.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Jan. 28, 2013
Investor and Institutional | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Overview Key Facts About BlackRock Small Cap Growth Equity Portfolio
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of BlackRock Small Cap Growth Equity Portfolio (“Small Cap Growth Equity” or the “Fund”), a series of BlackRock FundsSM (the “Trust”), is long-term capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of Small Cap Growth Equity. 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 the fund complex advised by BlackRock Advisors, LLC (“BlackRock”). More information about these and other discounts is available from your financial professional and in the “Details About the Share Classes” section on page 21 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-58 of the Fund’s statement of additional information.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	February 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when 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 147% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	147.00%
Expenses Deferred Charges [Text Block]	rr_ExpensesDeferredChargesTextBlock	A contingent deferred sales charge (“CDSC”) of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.
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 the fund complex advised by BlackRock Advisors, LLC (“BlackRock”).
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	25,000
Expense Example [Heading]	rr_ExpenseExampleHeading	Example:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes 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 your costs would be:
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 Strategies of the Fund
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Small Cap Growth Equity normally invests at least 80% of its net assets in equity securities issued by U.S. small capitalization companies which Fund management believes offer superior prospects for growth. Equity securities consist primarily of common stock, preferred stock, securities convertible into common stock and securities or other instruments whose price is linked to the value of common stock. The Fund management team focuses on U.S. small capitalization emerging growth companies. Although a universal definition of small-capitalization companies does not exist, the Fund generally defines these companies, at the time of the Fund’s investment, as those with market capitalizations comparable in size to the companies in the Russell 2000® Growth Index (between approximately $53 million and $3.771 billion as of June 30, 2012, the most recent rebalance date). In the future, the Fund may define small-capitalization companies using a different index or classification system. The Fund seeks to buy primarily common stock but also can invest in preferred stock, convertible securities and other equity securities. From time to time the Fund may invest in shares of companies through “new issues” or initial public offerings (“IPOs”).
Risk [Heading]	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Risk is inherent in all investing. The value of your investment in Small Cap Growth Equity, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund. Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock. Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions. Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles. Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money. “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering. Small Cap and Emerging Growth Securities Risk — Small cap or emerging growth companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The information shows you how Small Cap Growth Equity’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Russell 2000® Growth Index. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information shows you how Small Cap Growth Equity’s performance has varied year by year and provides some indication of the risks of investing in the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	(800) 882-0052
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://www.blackrock.com/funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	As with all such investments, past performance (before and after taxes) is not an indication of future results.
Bar Chart [Heading]	rr_BarChartHeading	Investor A Shares ANNUAL TOTAL RETURNS BlackRock Small Cap Growth Equity Portfolio As of 12/31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the ten-year period shown in the bar chart, the highest return for a quarter was 26.00% (quarter ended June 30, 2009) and the lowest return for a quarter was –28.84% (quarter ended December 31, 2008).
Performance Table Heading	rr_PerformanceTableHeading	As of 12/31/12 Average Annual Total Returns
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	However, the table includes all applicable fees and sales charges.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their 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 are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C and Institutional Shares will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C and Institutional Shares will vary.
Investor and Institutional | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.25%
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none	[1]
Management Fee	rr_ManagementFeesOverAssets	0.54%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.38%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.17%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.17%	[2]
1 Year	rr_ExpenseExampleYear01	638
3 Years	rr_ExpenseExampleYear03	877
5 Years	rr_ExpenseExampleYear05	1,135
10 Years	rr_ExpenseExampleYear10	1,871
2003	rr_AnnualReturn2003	54.65%
2004	rr_AnnualReturn2004	10.09%
2005	rr_AnnualReturn2005	6.11%
2006	rr_AnnualReturn2006	18.68%
2007	rr_AnnualReturn2007	14.97%
2008	rr_AnnualReturn2008	(40.08%)
2009	rr_AnnualReturn2009	34.16%	[3]
2010	rr_AnnualReturn2010	22.56%
2011	rr_AnnualReturn2011	(0.18%)
2012	rr_AnnualReturn2012	10.64%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	26.00%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(28.84%)
1 Year	rr_AverageAnnualReturnYear01	4.83%
5 Years	rr_AverageAnnualReturnYear05	0.62%	[3]
10 Years	rr_AverageAnnualReturnYear10	9.77%	[3]
Investor and Institutional | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO | Investor B Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	4.50%	[4]
Management Fee	rr_ManagementFeesOverAssets	0.54%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.53%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.07%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	2.07%	[2]
1 Year	rr_ExpenseExampleYear01	660
3 Years	rr_ExpenseExampleYear03	999
5 Years	rr_ExpenseExampleYear05	1,314
10 Years	rr_ExpenseExampleYear10	2,169
1 Year	rr_ExpenseExampleNoRedemptionYear01	210
3 Years	rr_ExpenseExampleNoRedemptionYear03	649
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,114
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,169
1 Year	rr_AverageAnnualReturnYear01	5.31%
5 Years	rr_AverageAnnualReturnYear05	0.49%	[3]
10 Years	rr_AverageAnnualReturnYear10	9.62%	[3]
Investor and Institutional | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO | Investor C Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[5]
Management Fee	rr_ManagementFeesOverAssets	0.54%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.45%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.99%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.99%	[2]
1 Year	rr_ExpenseExampleYear01	302
3 Years	rr_ExpenseExampleYear03	624
5 Years	rr_ExpenseExampleYear05	1,073
10 Years	rr_ExpenseExampleYear10	2,317
1 Year	rr_ExpenseExampleNoRedemptionYear01	202
3 Years	rr_ExpenseExampleNoRedemptionYear03	624
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,073
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,317
1 Year	rr_AverageAnnualReturnYear01	8.78%
5 Years	rr_AverageAnnualReturnYear05	0.82%	[3]
10 Years	rr_AverageAnnualReturnYear10	9.44%	[3]
Investor and Institutional | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO | Institutional Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Management Fee	rr_ManagementFeesOverAssets	0.54%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.28%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.82%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	0.82%	[2]
1 Year	rr_ExpenseExampleYear01	84
3 Years	rr_ExpenseExampleYear03	262
5 Years	rr_ExpenseExampleYear05	455
10 Years	rr_ExpenseExampleYear10	1,014
1 Year	rr_AverageAnnualReturnYear01	11.06%
5 Years	rr_AverageAnnualReturnYear05	2.11%	[3]
10 Years	rr_AverageAnnualReturnYear10	10.77%	[3]
Investor and Institutional | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO | Return After Taxes on Distributions | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	2.25%
5 Years	rr_AverageAnnualReturnYear05	0.03%	[3]
10 Years	rr_AverageAnnualReturnYear10	9.46%	[3]
Investor and Institutional | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO | Return After Taxes on Distributions and Sale of Shares | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	4.67%
5 Years	rr_AverageAnnualReturnYear05	0.36%	[3]
10 Years	rr_AverageAnnualReturnYear10	8.63%	[3]
Investor and Institutional | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO | Russell 2000® Growth Index (Reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	14.59%
5 Years	rr_AverageAnnualReturnYear05	3.49%	[3]
10 Years	rr_AverageAnnualReturnYear10	9.80%	[3]

[1] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[2] As described in the "Management of the Funds" section of the Fund's prospectus on pages 36-41, BlackRock has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) as a percentage of average daily net assets to 1.50% (for Investor A Shares), 2.28% (for Investor B and Investor C Shares) and 1.02% (for Institutional Shares) until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[3] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in settlement of litigation.

[4] The CDSC is 4.50% if shares are redeemed in less than one year. The CDSC for Investor B Shares decreases for redemptions made in subsequent years. After six years there is no CDSC on Investor B Shares. (See the section "Details About the Share Classes - Investor B Shares" in the Fund's prospectus for the complete schedule of CDSCs.)

[5] There is no CDSC on Investor C Shares after one year.

XML

Document and Entity Information	12 Months Ended
	Jan. 28, 2013
Risk/Return:
Document Type	485BPOS
Document Period End Date	Sep. 30, 2012
Registrant Name	BLACKROCK FUNDS
Central Index Key	0000844779
Amendment Flag	false
Document Creation Date	Jan. 28, 2013
Document Effective Date	Jan. 28, 2013
Prospectus Date	Jan. 28, 2013

XML

Service Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO

Fund Overview

Key Facts About BlackRock Mid-Cap Growth Equity Portfolio

Investment Objective

The investment objective of BlackRock Mid-Cap Growth Equity Portfolio (“Mid-Cap Growth Equity” or the “Fund”), a series of BlackRock Funds^SM (the “Trust”), is long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold Service Shares of Mid-Cap Growth Equity.

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

Annual Fund Operating Expenses		Service Shares BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO
Management Fee		0.80%
Distribution and/or Service (12b-1) Fees		0.25%
Other Expenses		1.24%
Total Annual Fund Operating Expenses		2.29%
Fee Waivers and/or Expense Reimbursements	[1]	(0.71%)
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	[1]	1.58%

Example:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes 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 your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Service Shares BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO	161	647	1,161	2,571

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 may indicate higher transaction costs and may result in higher taxes when 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 88% of the average value of its portfolio.

Principal Investment Strategies of the Fund

Mid-Cap Growth Equity normally invests at least 80% of its net assets in equity securities issued by U.S. mid-capitalization companies which Fund management believes have above-average earnings growth potential. Equity securities consist primarily of common stock, preferred stock, securities convertible into common stock and securities or other instruments whose price is linked to the value of common stock. Although a universal definition of mid-capitalization companies does not exist, the Fund generally defines these companies, at the time of the Fund’s investment, as those with market capitalizations comparable in size to the companies in the Russell Midcap^® Growth Index (between approximately $1.275 billion and $19.075 billion as of June 30, 2012, the most recent rebalance date). In the future, the Fund may define mid-capitalization companies using a different index or classification system. The Fund seeks to buy primarily common stock but also can invest in preferred stock, convertible securities and other equity securities. From time to time the Fund may invest in shares of companies through “new issues” or initial public offerings (“IPOs”).

The Fund may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities (commonly known as derivatives). The primary purpose of using derivatives is to attempt to reduce risk to the Fund as a whole (hedge), but they may also be used to maintain liquidity and commit cash pending investment. Fund management also may, but under normal market conditions generally does not intend to, use derivatives for speculation to increase returns.

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in Mid-Cap Growth Equity, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund.

• Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock.

• Derivatives Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives.

• Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions.

• Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles.

• Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage.

• Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money.

• Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies.

• “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering.

Performance Information

The information shows you how Mid-Cap Growth Equity’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Russell Midcap^® Growth Index. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.

Service Shares
ANNUAL TOTAL RETURNS
BlackRock Mid-Cap Growth Equity Portfolio
As of 12/31

During the ten-year period shown in the bar chart, the highest return for a quarter was 20.88% (quarter ended June 30, 2009) and the lowest return for a quarter was –28.88% (quarter ended December 31, 2008).

As of 12/31/12
Average Annual Total Returns

Average Annual Total Returns Service Shares	1 Year	5 Years		10 Years
BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO	10.41%	(0.34%)	[1]	7.81%	[1]
BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO Return After Taxes on Distributions	10.41%	(0.34%)	[1]	7.79%	[1]
BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO Return After Taxes on Distributions and Sale of Shares	6.76%	(0.29%)	[1]	6.92%	[1]
BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO Russell Midcap® Growth Index (Reflects no deduction for fees, expenses or taxes)	15.81%	3.23%	[1]	10.32%	[1]

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 the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

[1] As described in the "Management of the Funds" section of the Fund's prospectus on pages 25-30, BlackRock Advisors, LLC ("BlackRock") has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 1.58% of average daily net assets until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[1] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in settlement of litigation.

[1] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in settlement of litigation.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Jan. 28, 2013
Service Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Overview Key Facts About BlackRock Mid-Cap Growth Equity Portfolio
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of BlackRock Mid-Cap Growth Equity Portfolio (“Mid-Cap Growth Equity” or the “Fund”), a series of BlackRock FundsSM (the “Trust”), is long-term capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Service Shares of Mid-Cap Growth Equity.
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	February 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when 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 88% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	88.00%
Expense Example [Heading]	rr_ExpenseExampleHeading	Example:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes 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 your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Mid-Cap Growth Equity normally invests at least 80% of its net assets in equity securities issued by U.S. mid-capitalization companies which Fund management believes have above-average earnings growth potential. Equity securities consist primarily of common stock, preferred stock, securities convertible into common stock and securities or other instruments whose price is linked to the value of common stock. Although a universal definition of mid-capitalization companies does not exist, the Fund generally defines these companies, at the time of the Fund’s investment, as those with market capitalizations comparable in size to the companies in the Russell Midcap® Growth Index (between approximately $1.275 billion and $19.075 billion as of June 30, 2012, the most recent rebalance date). In the future, the Fund may define mid-capitalization companies using a different index or classification system. The Fund seeks to buy primarily common stock but also can invest in preferred stock, convertible securities and other equity securities. From time to time the Fund may invest in shares of companies through “new issues” or initial public offerings (“IPOs”). The Fund may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities (commonly known as derivatives). The primary purpose of using derivatives is to attempt to reduce risk to the Fund as a whole (hedge), but they may also be used to maintain liquidity and commit cash pending investment. Fund management also may, but under normal market conditions generally does not intend to, use derivatives for speculation to increase returns.
Risk [Heading]	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Risk is inherent in all investing. The value of your investment in Mid-Cap Growth Equity, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund. Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock. Derivatives Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives. Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions. Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles. Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage. Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money. Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies. “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The information shows you how Mid-Cap Growth Equity’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Russell Midcap® Growth Index. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information shows you how Mid-Cap Growth Equity’s performance has varied year by year and provides some indication of the risks of investing in the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	(800) 882-0052
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://www.blackrock.com/funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	As with all such investments, past performance (before and after taxes) is not an indication of future results.
Bar Chart [Heading]	rr_BarChartHeading	Service Shares ANNUAL TOTAL RETURNS BlackRock Mid-Cap Growth Equity Portfolio As of 12/31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the ten-year period shown in the bar chart, the highest return for a quarter was 20.88% (quarter ended June 30, 2009) and the lowest return for a quarter was –28.88% (quarter ended December 31, 2008).
Performance Table Heading	rr_PerformanceTableHeading	As of 12/31/12 Average Annual Total Returns
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	However, the table includes all applicable fees and sales charges.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Service Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO | Service Shares
Risk/Return:	rr_RiskReturnAbstract
Management Fee	rr_ManagementFeesOverAssets	0.80%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	1.24%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.29%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.71%)	[1]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.58%	[1]
1 Year	rr_ExpenseExampleYear01	161
3 Years	rr_ExpenseExampleYear03	647
5 Years	rr_ExpenseExampleYear05	1,161
10 Years	rr_ExpenseExampleYear10	2,571
2003	rr_AnnualReturn2003	33.61%
2004	rr_AnnualReturn2004	15.26%
2005	rr_AnnualReturn2005	10.50%
2006	rr_AnnualReturn2006	5.92%
2007	rr_AnnualReturn2007	19.71%
2008	rr_AnnualReturn2008	(46.25%)
2009	rr_AnnualReturn2009	49.00%	[2]
2010	rr_AnnualReturn2010	15.01%
2011	rr_AnnualReturn2011	(3.32%)
2012	rr_AnnualReturn2012	10.41%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	20.88%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(28.88%)
1 Year	rr_AverageAnnualReturnYear01	10.41%
5 Years	rr_AverageAnnualReturnYear05	(0.34%)	[2]
10 Years	rr_AverageAnnualReturnYear10	7.81%	[2]
Service Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO | Return After Taxes on Distributions | Service Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	10.41%
5 Years	rr_AverageAnnualReturnYear05	(0.34%)	[2]
10 Years	rr_AverageAnnualReturnYear10	7.79%	[2]
Service Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO | Return After Taxes on Distributions and Sale of Shares | Service Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	6.76%
5 Years	rr_AverageAnnualReturnYear05	(0.29%)	[2]
10 Years	rr_AverageAnnualReturnYear10	6.92%	[2]
Service Shares | BLACKROCK MID CAP GROWTH EQUITY PORTFOLIO | Russell Midcap® Growth Index (Reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	15.81%
5 Years	rr_AverageAnnualReturnYear05	3.23%	[2]
10 Years	rr_AverageAnnualReturnYear10	10.32%	[2]

[1] As described in the "Management of the Funds" section of the Fund's prospectus on pages 25-30, BlackRock Advisors, LLC ("BlackRock") has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 1.58% of average daily net assets until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[2] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in settlement of litigation.

XML

Investor and Institutional | BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO

Fund Overview

Key Facts About BlackRock Small Cap Growth Equity Portfolio

Investment Objective

The investment objective of BlackRock Small Cap Growth Equity Portfolio (“Small Cap Growth Equity” or the “Fund”), a series of BlackRock Funds^SM (the “Trust”), is long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of Small Cap Growth Equity. 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 the fund complex advised by BlackRock Advisors, LLC (“BlackRock”). More information about these and other discounts is available from your financial professional and in the “Details About the Share Classes” section on page 21 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-58 of the Fund’s statement of additional information.

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Investor and Institutional BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO	Investor A Shares		Investor B Shares		Investor C Shares		Institutional Shares
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	5.25%		none		none		none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	none	[1]	4.50%	[2]	1.00%	[3]	none

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

Annual Fund Operating Expenses Investor and Institutional BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO		Investor A Shares	Investor B Shares	Investor C Shares	Institutional Shares
Management Fee		0.54%	0.54%	0.54%	0.54%
Distribution and/or Service (12b-1) Fees		0.25%	1.00%	1.00%	none
Other Expenses		0.38%	0.53%	0.45%	0.28%
Total Annual Fund Operating Expenses		1.17%	2.07%	1.99%	0.82%
Fee Waivers and/or Expense Reimbursements	[1]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	[1]	1.17%	2.07%	1.99%	0.82%

Example:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes 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 your costs would be:

Expense Example Investor and Institutional BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO (USD $)	1 Year	3 Years	5 Years	10 Years
Investor A Shares	638	877	1,135	1,871
Investor B Shares	660	999	1,314	2,169
Investor C Shares	302	624	1,073	2,317
Institutional Shares	84	262	455	1,014

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

Expense Example, No Redemption Investor and Institutional BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO (USD $)	1 Year	3 Years	5 Years	10 Years
Investor B Shares	210	649	1,114	2,169
Investor C Shares	202	624	1,073	2,317

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 may indicate higher transaction costs and may result in higher taxes when 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 147% of the average value of its portfolio.

Principal Investment Strategies of the Fund

Small Cap Growth Equity normally invests at least 80% of its net assets in equity securities issued by U.S. small capitalization companies which Fund management believes offer superior prospects for growth. Equity securities consist primarily of common stock, preferred stock, securities convertible into common stock and securities or other instruments whose price is linked to the value of common stock. The Fund management team focuses on U.S. small capitalization emerging growth companies. Although a universal definition of small-capitalization companies does not exist, the Fund generally defines these companies, at the time of the Fund’s investment, as those with market capitalizations comparable in size to the companies in the Russell 2000^® Growth Index (between approximately $53 million and $3.771 billion as of June 30, 2012, the most recent rebalance date). In the future, the Fund may define small-capitalization companies using a different index or classification system. The Fund seeks to buy primarily common stock but also can invest in preferred stock, convertible securities and other equity securities. From time to time the Fund may invest in shares of companies through “new issues” or initial public offerings (“IPOs”).

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in Small Cap Growth Equity, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund.

• Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock.

• Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions.

• Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles.

• Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money.

• “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering.

• Small Cap and Emerging Growth Securities Risk — Small cap or emerging growth companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.

Performance Information

The information shows you how Small Cap Growth Equity’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Russell 2000^® Growth Index. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.

Investor A Shares
ANNUAL TOTAL RETURNS
BlackRock Small Cap Growth Equity Portfolio
As of 12/31

During the ten-year period shown in the bar chart, the highest return for a quarter was 26.00% (quarter ended June 30, 2009) and the lowest return for a quarter was –28.84% (quarter ended December 31, 2008).

As of 12/31/12
Average Annual Total Returns

Average Annual Total Returns Investor and Institutional BLACKROCK SMALL CAP GROWTH EQUITY PORTFOLIO	1 Year	5 Years		10 Years
Investor A	4.83%	0.62%	[1]	9.77%	[1]
Investor A Return After Taxes on Distributions	2.25%	0.03%	[1]	9.46%	[1]
Investor A Return After Taxes on Distributions and Sale of Shares	4.67%	0.36%	[1]	8.63%	[1]
Investor B	5.31%	0.49%	[1]	9.62%	[1]
Investor C	8.78%	0.82%	[1]	9.44%	[1]
Institutional	11.06%	2.11%	[1]	10.77%	[1]
Russell 2000® Growth Index (Reflects no deduction for fees, expenses or taxes)	14.59%	3.49%	[1]	9.80%	[1]

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 the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C and Institutional Shares will vary.

[1] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[2] The CDSC is 4.50% if shares are redeemed in less than one year. The CDSC for Investor B Shares decreases for redemptions made in subsequent years. After six years there is no CDSC on Investor B Shares. (See the section "Details About the Share Classes - Investor B Shares" in the Fund's prospectus for the complete schedule of CDSCs.)

[3] There is no CDSC on Investor C Shares after one year.

[1] As described in the "Management of the Funds" section of the Fund's prospectus on pages 36-41, BlackRock has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) as a percentage of average daily net assets to 1.50% (for Investor A Shares), 2.28% (for Investor B and Investor C Shares) and 1.02% (for Institutional Shares) until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[1] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in settlement of litigation.

[1] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in settlement of litigation.