485BPOS

As filed with the Securities and Exchange Commission on December 10, 2012

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. 253	x
and/or
REGISTRATION STATEMENT
UNDER
THE INVESTMENT COMPANY ACT OF 1940	x
Amendment No. 255	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:

John A. MacKinnon, 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 Registration Statement under 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 the 10^th day of December, 2012.

BLACKROCK FUNDSSM, ON BEHALF OF BLACKROCK EMERGING MARKETS LONG/SHORT EQUITY FUND
(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 below by the following persons in the capacities and on the dates indicated.

Signature	Title	Date
/s/    JOHN M. PERLOWSKI John M. Perlowski	President and Chief Executive Officer (Principal Executive Officer)	December 10, 2012
/S/    NEAL J. ANDREWS Neal J. Andrews	Chief Financial Officer (Principal Financial and Accounting Officer)	December 10, 2012
DAVID O. BEIM* David O. Beim	Trustee
RONALD W. FORBES* Ronald W. Forbes	Trustee
DR. MATINA S. HORNER* Dr. Matina S. Horner	Trustee
RODNEY D. JOHNSON* Rodney D. Johnson	Trustee
HERBERT I. LONDON* Herbert I. London	Trustee
IAN A. MACKINNON* Ian A. MacKinnon	Trustee
CYNTHIA A. MONTGOMERY* Cynthia A. Montgomery	Trustee
JOSEPH P. PLATT* Joseph P. Platt	Trustee
ROBERT C. ROBB, JR.* Robert C. Robb, Jr.	Trustee

TOBY ROSENBLATT* Toby Rosenblatt	Trustee
KENNETH L. URISH* Kenneth L. Urish	Trustee
FREDERICK W. WINTER* Frederick W. Winter	Trustee
PAUL L. AUDET* Paul L. Audet	Trustee
HENRY GABBAY* Henry Gabbay	Trustee

*By:	/S/    BENJAMIN ARCHIBALD	December 10, 2012
	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	Nov. 28, 2012
Document Creation Date	dei_DocumentCreationDate	Nov. 28, 2012

XML

BlackRock Emerging Markets Long/Short Equity Fund

Fund Overview

Key Facts About BlackRock Emerging Markets Long/Short Equity Fund

Investment Objective

The investment objective of BlackRock Emerging Markets Long/Short Equity Fund (the “Fund”), a series of BlackRock Funds^SM (the “Trust”), is to seek total return over the long term.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 18 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-58 of Part II of the Fund’s statement of additional information (the “SAI”).

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees BlackRock Emerging Markets Long/Short Equity Fund	Investor A Shares		Investor C Shares		Institutional Shares
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	5.25%		none		none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	none	[1]	1.00%	[2]	none

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

Annual Fund Operating Expenses BlackRock Emerging Markets Long/Short Equity Fund		Investor A Shares	Investor C Shares	Institutional Shares
Management Fee		1.50%	1.50%	1.50%
Distribution and/or Service (12b-1) Fees		0.25%	1.00%	none
Other Expenses		0.44%	0.50%	0.63%
Total Annual Fund Operating Expenses		2.19%	3.00%	2.13%
Fee Waivers and/or Expense Reimbursements	[1]	(0.19%)	(0.25%)	(0.38%)
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	[1]	2.00%	2.75%	1.75%

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. This 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 BlackRock Emerging Markets Long/Short Equity Fund (USD $)	1 Year	3 Years	5 Years	10 Years
Investor A Shares	717	1,157	1,621	2,902
Investor C Shares	378	904	1,555	3,300
Institutional Shares	178	630	1,109	2,432

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

Expense Example, No Redemption (USD $)	1 Year	3 Years	5 Years	10 Years
BlackRock Emerging Markets Long/Short Equity Fund Investor C Shares	278	904	1,555	3,300

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. For the period October 6, 2011 (commencement of operations) through July 31, 2012, the Fund’s portfolio turnover rate was 0% of the average value of its portfolio.

Principal Investment Strategies of the Fund

Under normal conditions, the Fund invests at least 80% of its total assets in global equity instruments and related derivative instruments issued by, or tied economically to, companies in emerging markets. BlackRock considers an emerging market country to include any country that is: 1) generally recognized to be an emerging market country by the international financial community, including the World Bank; 2) classified by the United Nations as a developing country; or 3) included in the MSCI Emerging Markets Index^SM. BlackRock determines that an investment is tied economically to an emerging market if such investment satisfies one or more of the following conditions: 1) the issuer’s primary trading market is in an emerging market; 2) the issuer is organized under the laws of, derives at least 50% of its revenue from, or has at least 50% of its assets in emerging markets; 3) the investment is included in an index representative of emerging markets; and 4) the investment is exposed to the economic risks and returns of emerging markets. The Fund may invest in securities of issuers of any market capitalization and in securities denominated in either U.S. dollars or foreign currencies.

The Fund pursues its investment objective by taking both long and short positions in a variety of global equity instruments. The Fund expects to maintain long and short positions primarily through the use of swap agreements and other derivative instruments, and may invest in such instruments without limitation. Although the Fund intends to maintain an overall long position in its portfolio investments, the Fund generally expects to maintain significant short positions in equity securities and equity-related instruments. In certain circumstances, these short positions may approach or reach the size of the overall long position. The use of both long and short positions better enables the Fund to seek to produce returns that are uncorrelated to those available by investing in the market as a whole. A long position arises where the Fund holds a security in its portfolio or maintains a position through a derivative instrument that provides economic exposure similar to direct ownership of the security. The Fund will have a short position where it sells a security it does not own by delivery of a borrowed security or has entered into a derivative instrument that provides economic exposure similar to a short sale of the security. The Fund takes long positions primarily in securities that BlackRock has identified as attractive and short positions in such securities that BlackRock has identified as overvalued or poised for underperformance.

The Fund may invest up to 20% of its assets in equity instruments issued by or based on companies located outside of emerging markets. When consistent with the Fund’s investment objective, these investments may include short-term investments such as cash and cash equivalents, U.S. Government and agency securities, money market funds (including funds that may be affiliated with or sponsored or managed by BlackRock), commercial paper, certificates of deposit and other bank deposits and bankers’ acceptances.

Equity instruments consist of:

• Derivative securities or instruments such as options, futures, contracts for difference, forward contracts and swaps (including interest rate swaps and total return swaps), the value of which is based on a common stock or group of common stocks. A contract for difference offers exposure to price changes in an underlying security without ownership of such security, typically by providing investors the ability to trade on margin. The Fund may utilize derivative instruments as a significant part of its strategy.

• Common stock

• Depositary receipts

The Fund may engage in active and frequent trading of portfolio securities to achieve its primary investment strategies.

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in the Fund, 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 certain risks of investing in the Fund.

• Depositary Receipts Risk — The issuers of unsponsored depositary receipts are not obligated to disclose information that is, in the United States, considered material. Therefore, there may be less information available regarding these issuers and there may not be a correlation between such information and the market value of the depositary receipts. Depositary receipts are generally subject to the same risks as the foreign securities that they evidence or into which they may be converted.

• 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.
  
  Risks Specific to Certain Derivatives Used by the Fund

  Swaps — Swap agreements involve the risk that the party with whom the Fund has entered into the swap will default on its obligation to pay the Fund and the risk that the Fund will not be able to meet its obligations to pay the other party to the agreement. The income tax treatment of swap agreements is unsettled and may be subject to future legislation, regulation or administrative pronouncements issued by the Internal Revenue Service. If such future guidance limits the Fund’s ability to use derivatives, the Fund may have to find other ways of achieving its investment objective.
  
  Forward Foreign Currency Exchange Contracts — Forward foreign currency exchange contracts do not eliminate fluctuations in the value of non-U.S. securities but rather allow the Fund to establish a fixed rate of exchange for a future point in time. This strategy can have the effect of reducing returns and minimizing opportunities for gain.
  
  Contracts for Difference — Contracts for difference are subject to liquidity risk because the liquidity of contracts for difference is based on the liquidity of the underlying instrument, and are subject to counterparty risk, i.e., the risk that the counterparty to the contracts for difference transaction may be unable or unwilling to make payments or to otherwise honor its financial obligations under the terms of the contract. To the extent that there is an imperfect correlation between the return on the Fund’s obligation to its counterparty under the contract for difference and the return on related assets in its portfolio, the contracts for difference transaction may increase the Fund’s financial risk. Contracts for difference, like many other derivative instruments, involve the risk that, if the derivative security declines in value, additional margin would be required to maintain the margin level. The seller may require the Fund to deposit additional sums to cover this, and this may be at short notice. If additional margin is not provided in time, the seller may liquidate the positions at a loss for which the Fund is liable. Contracts for difference are not registered with the Securities and Exchange Commission (the “SEC”) or any U.S. regulator, and are not subject to U.S. regulation.

  To the extent derivatives are utilized to implement the Fund’s investment strategies, these transactions involve the risks described below with respect to investments in emerging market equity securities and short sales of securities.

• Emerging Markets Risk — Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets.

• 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.

• Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include:
  
  

  — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight.

  — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio.

  — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position.

  — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries.

  — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws.

  — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments.

• High Portfolio Turnover Risk — The Fund may engage in active and frequent trading of its investments. High portfolio turnover may result in increased transaction costs to the Fund, which may be mitigated to the extent such turnover is of certain types of derivative instruments. It may also result in a change in the Fund’s market exposure over short periods of time. High portfolio turnover may also result in the realization and distribution to shareholders of higher gains or losses as compared to a fund with less active trading policies and could increase an investor’s tax liability unless shares are held through a tax-deferred or exempt vehicle. These effects of higher than normal portfolio turnover may adversely affect Fund performance.

• 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. As an open-end investment company registered with the SEC, the Fund is subject to the federal securities laws, including the Investment Company Act of 1940, as amended, the rules thereunder, and various SEC and SEC staff interpretive positions. In accordance with these laws, rules and positions, the Fund must “set aside” liquid assets (often referred to as “asset segregation”), or engage in other SEC- or staff-approved measures, to “cover” open positions with respect to certain kinds of instruments. 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.

• Short Sales Risk — Because making short sales in securities that it does not own exposes the Fund to the risks associated with those securities, such short sales involve speculative exposure risk. The Fund may incur a loss as a result of a short sale if the price of the security increases between the date of the short sale and the date on which the Fund replaces the security sold short. Short sale transactions involve leverage because they can provide investment exposure in an amount exceeding the initial investment.

• 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.

• Tax and Regulatory Risk — Certain aspects of the tax treatment of derivative instruments, including swap agreements, are currently unclear and may be affected by changes in legislation, regulations or other legally binding authority that could affect the character, timing and amount of the Fund’s taxable income or gains and distributions. Other future regulatory developments may also impact the Fund’s ability to invest or remain invested in certain derivatives.

Performance Information

Because the Fund does not have a full calendar year of operations, it does not have performance information an investor would find useful in evaluating the risks of investing in the Fund. The Fund’s benchmark is the BofA Merrill Lynch 3-Month U.S. Treasury Bill Index.

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

[1] As described in the "Management of the Fund" section of the Fund's prospectus on pages 32-36, 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 2.00% of average daily net assets (for Investor A Shares), 2.75% of average daily net assets (for Investor C Shares) and 1.75% of average daily net assets (for Institutional Shares) until December 1, 2013. The Fund may have to repay some of these waivers and 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.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Nov. 28, 2012
BlackRock Emerging Markets Long/Short Equity Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Overview Key Facts About BlackRock Emerging Markets Long/Short Equity Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of BlackRock Emerging Markets Long/Short Equity Fund (the “Fund”), a series of BlackRock FundsSM (the “Trust”), is to seek total return over the long term.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 18 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-58 of Part II of the Fund’s statement of additional information (the “SAI”).
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	December 1, 2013
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. For the period October 6, 2011 (commencement of operations) through July 31, 2012, the Fund’s portfolio turnover rate was 0% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	0.00%
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. This 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	Under normal conditions, the Fund invests at least 80% of its total assets in global equity instruments and related derivative instruments issued by, or tied economically to, companies in emerging markets. BlackRock considers an emerging market country to include any country that is: 1) generally recognized to be an emerging market country by the international financial community, including the World Bank; 2) classified by the United Nations as a developing country; or 3) included in the MSCI Emerging Markets IndexSM. BlackRock determines that an investment is tied economically to an emerging market if such investment satisfies one or more of the following conditions: 1) the issuer’s primary trading market is in an emerging market; 2) the issuer is organized under the laws of, derives at least 50% of its revenue from, or has at least 50% of its assets in emerging markets; 3) the investment is included in an index representative of emerging markets; and 4) the investment is exposed to the economic risks and returns of emerging markets. The Fund may invest in securities of issuers of any market capitalization and in securities denominated in either U.S. dollars or foreign currencies. The Fund pursues its investment objective by taking both long and short positions in a variety of global equity instruments. The Fund expects to maintain long and short positions primarily through the use of swap agreements and other derivative instruments, and may invest in such instruments without limitation. Although the Fund intends to maintain an overall long position in its portfolio investments, the Fund generally expects to maintain significant short positions in equity securities and equity-related instruments. In certain circumstances, these short positions may approach or reach the size of the overall long position. The use of both long and short positions better enables the Fund to seek to produce returns that are uncorrelated to those available by investing in the market as a whole. A long position arises where the Fund holds a security in its portfolio or maintains a position through a derivative instrument that provides economic exposure similar to direct ownership of the security. The Fund will have a short position where it sells a security it does not own by delivery of a borrowed security or has entered into a derivative instrument that provides economic exposure similar to a short sale of the security. The Fund takes long positions primarily in securities that BlackRock has identified as attractive and short positions in such securities that BlackRock has identified as overvalued or poised for underperformance. The Fund may invest up to 20% of its assets in equity instruments issued by or based on companies located outside of emerging markets. When consistent with the Fund’s investment objective, these investments may include short-term investments such as cash and cash equivalents, U.S. Government and agency securities, money market funds (including funds that may be affiliated with or sponsored or managed by BlackRock), commercial paper, certificates of deposit and other bank deposits and bankers’ acceptances. Equity instruments consist of: Derivative securities or instruments such as options, futures, contracts for difference, forward contracts and swaps (including interest rate swaps and total return swaps), the value of which is based on a common stock or group of common stocks. A contract for difference offers exposure to price changes in an underlying security without ownership of such security, typically by providing investors the ability to trade on margin. The Fund may utilize derivative instruments as a significant part of its strategy. Common stock Depositary receipts The Fund may engage in active and frequent trading of portfolio securities to achieve its primary investment strategies.
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 the Fund, 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 certain risks of investing in the Fund. Depositary Receipts Risk — The issuers of unsponsored depositary receipts are not obligated to disclose information that is, in the United States, considered material. Therefore, there may be less information available regarding these issuers and there may not be a correlation between such information and the market value of the depositary receipts. Depositary receipts are generally subject to the same risks as the foreign securities that they evidence or into which they may be converted. 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. Risks Specific to Certain Derivatives Used by the Fund Swaps — Swap agreements involve the risk that the party with whom the Fund has entered into the swap will default on its obligation to pay the Fund and the risk that the Fund will not be able to meet its obligations to pay the other party to the agreement. The income tax treatment of swap agreements is unsettled and may be subject to future legislation, regulation or administrative pronouncements issued by the Internal Revenue Service. If such future guidance limits the Fund’s ability to use derivatives, the Fund may have to find other ways of achieving its investment objective. Forward Foreign Currency Exchange Contracts — Forward foreign currency exchange contracts do not eliminate fluctuations in the value of non-U.S. securities but rather allow the Fund to establish a fixed rate of exchange for a future point in time. This strategy can have the effect of reducing returns and minimizing opportunities for gain. Contracts for Difference — Contracts for difference are subject to liquidity risk because the liquidity of contracts for difference is based on the liquidity of the underlying instrument, and are subject to counterparty risk, i.e., the risk that the counterparty to the contracts for difference transaction may be unable or unwilling to make payments or to otherwise honor its financial obligations under the terms of the contract. To the extent that there is an imperfect correlation between the return on the Fund’s obligation to its counterparty under the contract for difference and the return on related assets in its portfolio, the contracts for difference transaction may increase the Fund’s financial risk. Contracts for difference, like many other derivative instruments, involve the risk that, if the derivative security declines in value, additional margin would be required to maintain the margin level. The seller may require the Fund to deposit additional sums to cover this, and this may be at short notice. If additional margin is not provided in time, the seller may liquidate the positions at a loss for which the Fund is liable. Contracts for difference are not registered with the Securities and Exchange Commission (the “SEC”) or any U.S. regulator, and are not subject to U.S. regulation. To the extent derivatives are utilized to implement the Fund’s investment strategies, these transactions involve the risks described below with respect to investments in emerging market equity securities and short sales of securities. Emerging Markets Risk — Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets. 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. Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include: — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight. — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio. — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position. — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries. — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws. — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments. High Portfolio Turnover Risk — The Fund may engage in active and frequent trading of its investments. High portfolio turnover may result in increased transaction costs to the Fund, which may be mitigated to the extent such turnover is of certain types of derivative instruments. It may also result in a change in the Fund’s market exposure over short periods of time. High portfolio turnover may also result in the realization and distribution to shareholders of higher gains or losses as compared to a fund with less active trading policies and could increase an investor’s tax liability unless shares are held through a tax-deferred or exempt vehicle. These effects of higher than normal portfolio turnover may adversely affect Fund performance. 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. As an open-end investment company registered with the SEC, the Fund is subject to the federal securities laws, including the Investment Company Act of 1940, as amended, the rules thereunder, and various SEC and SEC staff interpretive positions. In accordance with these laws, rules and positions, the Fund must “set aside” liquid assets (often referred to as “asset segregation”), or engage in other SEC- or staff-approved measures, to “cover” open positions with respect to certain kinds of instruments. 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. Short Sales Risk — Because making short sales in securities that it does not own exposes the Fund to the risks associated with those securities, such short sales involve speculative exposure risk. The Fund may incur a loss as a result of a short sale if the price of the security increases between the date of the short sale and the date on which the Fund replaces the security sold short. Short sale transactions involve leverage because they can provide investment exposure in an amount exceeding the initial investment. 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. Tax and Regulatory Risk — Certain aspects of the tax treatment of derivative instruments, including swap agreements, are currently unclear and may be affected by changes in legislation, regulations or other legally binding authority that could affect the character, timing and amount of the Fund’s taxable income or gains and distributions. Other future regulatory developments may also impact the Fund’s ability to invest or remain invested in certain derivatives.
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	Because the Fund does not have a full calendar year of operations, it does not have performance information an investor would find useful in evaluating the risks of investing in the Fund. The Fund’s benchmark is the BofA Merrill Lynch 3-Month U.S. Treasury Bill Index.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	Because the Fund does not have a full calendar year of operations, it does not have performance information an investor would find useful in evaluating the risks of investing in the Fund.
BlackRock Emerging Markets Long/Short Equity Fund | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.25%
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none	[1]
Management Fee	rr_ManagementFeesOverAssets	1.50%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.44%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.19%
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	2.00%	[2]
1 Year	rr_ExpenseExampleYear01	717
3 Years	rr_ExpenseExampleYear03	1,157
5 Years	rr_ExpenseExampleYear05	1,621
10 Years	rr_ExpenseExampleYear10	2,902
BlackRock Emerging Markets Long/Short Equity Fund | Investor C Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[3]
Management Fee	rr_ManagementFeesOverAssets	1.50%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.50%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	3.00%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.25%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	2.75%	[2]
1 Year	rr_ExpenseExampleYear01	378
3 Years	rr_ExpenseExampleYear03	904
5 Years	rr_ExpenseExampleYear05	1,555
10 Years	rr_ExpenseExampleYear10	3,300
1 Year	rr_ExpenseExampleNoRedemptionYear01	278
3 Years	rr_ExpenseExampleNoRedemptionYear03	904
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,555
10 Years	rr_ExpenseExampleNoRedemptionYear10	3,300
BlackRock Emerging Markets Long/Short Equity Fund | Institutional Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Management Fee	rr_ManagementFeesOverAssets	1.50%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.63%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.13%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.38%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.75%	[2]
1 Year	rr_ExpenseExampleYear01	178
3 Years	rr_ExpenseExampleYear03	630
5 Years	rr_ExpenseExampleYear05	1,109
10 Years	rr_ExpenseExampleYear10	2,432

[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 Fund" section of the Fund's prospectus on pages 32-36, 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 2.00% of average daily net assets (for Investor A Shares), 2.75% of average daily net assets (for Investor C Shares) and 1.75% of average daily net assets (for Institutional Shares) until December 1, 2013. The Fund may have to repay some of these waivers and 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] There is no CDSC on Investor C Shares after one year.

XML

Document and Entity Information	12 Months Ended
	Nov. 28, 2012
Risk/Return:
Document Type	485BPOS
Document Period End Date	Jul. 31, 2012
Registrant Name	BLACKROCK FUNDS
Central Index Key	0000844779
Amendment Flag	false
Document Creation Date	Nov. 28, 2012
Document Effective Date	Nov. 28, 2012
Prospectus Date	Nov. 28, 2012