485BPOS

As filed with the Securities and Exchange Commission on December 7, 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. 252	x
and/or

REGISTRATION STATEMENT

UNDER
THE INVESTMENT COMPANY ACT OF 1940	x
Amendment No. 254	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. Sidley Austin LLP 787 Seventh Avenue New York, New York 10019-6018 Benjamin Archibald, Esq. BlackRock Advisors, LLC 55 East 52^nd Street 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 7^th day of December, 2012.

BLACKROCK FUNDSSM, ON BEHALF OF BLACKROCK GLOBAL LONG/SHORT CREDIT 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 7, 2012
/S/ NEAL J. ANDREWS Neal J. Andrews	Chief Financial Officer (Principal Financial and Accounting Officer)	December 7, 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

2

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 7, 2012
	Benjamin Archibald (Attorney-in-Fact)

3

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

4

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 Global Long/Short Credit Fund

Fund Overview

Key Facts About BlackRock Global Long/Short Credit Fund

Investment Objective

The investment objective of BlackRock Global Long/Short Credit Fund (the “Fund”), a series of BlackRock Funds^SM (the “Trust”), is to seek absolute total returns over a complete market cycle.

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 26 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-71 of the Fund’s statement of additional information (the “SAI”).

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees BlackRock Global Long/Short Credit Fund	Investor A Shares		Investor C Shares		Institutional Shares
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	4.00%		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 Global Long/Short Credit Fund		Investor A Shares	Investor C Shares	Institutional Shares
Management Fee		0.95%	0.95%	0.95%
Distribution and/or Service (12b-1) Fees		0.25%	1.00%	none
Other Expenses		0.73%	0.71%	0.78%
Interest Expense		0.26%	0.26%	0.26%
Miscellaneous Other Expenses		0.47%	0.45%	0.52%
Acquired Fund Fees and Expenses	[1]	0.11%	0.11%	0.11%
Total Annual Fund Operating Expenses	[1]	2.04%	2.77%	1.84%
Fee Waivers and/or Expense Reimbursements	[2]	(0.27%)	(0.25%)	(0.27%)
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	[2]	1.77%	2.52%	1.57%

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 BlackRock Global Long/Short Credit Fund (USD $)	1 Year	3 Years	5 Years	10 Years
Investor A Shares	573	989	1,430	2,653
Investor C Shares	355	836	1,442	3,081
Institutional Shares	160	552	970	2,136

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 Global Long/Short Credit Fund Investor C Shares	255	836	1,442	3,081

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 September 30, 2011 (commencement of operations) through July 31, 2012, the Fund’s portfolio turnover rate was 355% of the average value of its portfolio.

Principal Investment Strategies of the Fund

The Fund seeks to provide absolute total returns over a complete market cycle through diversified long and short exposure to the global fixed income markets. A complete market cycle for fixed income funds such as the Fund is typically three to five years.

Under normal circumstances, the Fund invests at least 80% of its total assets in credit-related instruments, including, but not limited to, U.S. Government and agency securities, foreign government and supranational debt securities, corporate bonds, including bonds of companies principally engaged in the aircraft or air transportation industries, mortgage-related securities and asset-backed securities, collateralized debt and loan obligations, including bonds collateralized by aircraft and/or aircraft equipment, emerging market debt securities, preferred securities, structured products, mezzanine securities, senior secured floating rate and fixed rate loans or debt, second lien or other subordinated or unsecured floating rate and fixed rate loans or debt, convertible debt securities, and derivatives with similar economic characteristics. The Fund may invest in fixed, variable and floating rate instruments, including participations and assignments, of any duration or maturity.

Under normal circumstances, the Fund anticipates it will allocate a substantial amount (approximately 40% or more, unless market conditions are not deemed favorable by BlackRock, in which case the Fund would invest at least 30%) of its total assets in securities (or derivatives with similar economic characteristics) of (i) foreign government issuers, (ii) issuers organized or located outside the U.S., (iii) issuers whose securities primarily trade in a market located outside the U.S., or (iv) issuers doing a substantial amount of business outside the U.S., which the Fund considers to be companies that derive at least 50% of their revenue or profits from business outside the U.S. or have at least 50% of their sales or assets outside the U.S. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund may invest in credit-related instruments rated below investment grade or deemed equivalent by Fund management, which are commonly referred to as “junk bonds.”

Generally, the Fund’s average maturity is expected to be less than 6 years.

The Fund may invest in non-U.S. dollar denominated investments including investments denominated in European and Asian currencies and in other non-U.S. and emerging market currencies. The Fund’s investments in non-U.S. dollar based assets may be made on a currency hedged or unhedged basis.

The Fund may invest up to 20% of its total assets in equity instruments, including common stock, depositary receipts, rights, warrants and other instruments whose price is linked to the value of common stock. The Fund may hold long or short positions in equity instruments, and may invest in equity instruments of issuers of any market capitalization.

The Fund may also gain both long and short exposure to credit-related instruments by entering into a series of purchase and sale contracts or by investing in, among other instruments, swaps, including total return, credit default, index and interest rate swaps; options; forward contracts; futures contracts and options on futures contracts that provide long or short exposure to other credit obligations; credit-linked notes that provide long or short exposure to other credit obligations; repurchase agreements; reverse repurchase agreements; dollar rolls; exchange-traded funds and closed-end registered investment companies, which may be managed by BlackRock or one of its affiliates; and other similar transactions.

The Fund may engage in short sales for hedging purposes or to enhance total return. The Fund also may make short sales “against the box” without limitation. In this type of short sale, at the time of the sale, the Fund owns or has the immediate and unconditional right to acquire the identical security at no additional cost.

As part of its normal operations, the Fund may hold high quality money market securities and invest in money market funds, including affiliated money market funds, pending investments or when it expects to need cash to pay redeeming shareholders. The Fund also may invest in these securities in order to achieve its investment goal. Money market securities are short term securities consisting primarily of short term U.S. Government securities, U.S. Government agency securities, securities issued by U.S. Government sponsored enterprises and U.S. Government instrumentalities, bank obligations, commercial paper, including asset backed commercial paper, corporate notes and repurchase agreements.

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

The Fund may borrow from banks for investment purposes.

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.

• Air Transportation Industry Risks — The air transportation industry can be significantly affected by competition within the industry, domestic and foreign economies, government regulation, labor relations, and the price of fuel. Airline deregulation has substantially diminished the government’s role in the air transport industry while promoting an increased level of competition. However, regulations and policies of various domestic and foreign governments can still affect the profitability of individual carriers as well as the entire industry.

• Borrowing Risk — Borrowing may exaggerate changes in the net asset value of Fund shares and in the return on the Fund’s portfolio. Borrowing will cost the Fund interest expense and other fees. The costs of borrowing may reduce the Fund’s return. Borrowing may cause the Fund to liquidate positions when it may not be advantageous to do so to satisfy its obligations.

• Collateralized Debt Obligations Risks — Collateralized debt obligations are subject to credit, interest rate, valuation, prepayment and extension risks. These securities also are subject to risk of default on the underlying asset, particularly during periods of economic downturn.

• 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 risk as apply to the underlying common stock.

• Corporate Loans Risk — Commercial banks and other financial institutions or institutional investors make corporate loans to companies that need capital to grow or restructure. Borrowers generally pay interest on corporate loans at rates that change in response to changes in market interest rates such as the London Interbank Offered Rate (“LIBOR”) or the prime rates of U.S. banks. As a result, the value of corporate loan investments is generally less exposed to the adverse effects of shifts in market interest rates than investments that pay a fixed rate of interest. The market for corporate loans may be subject to irregular trading activity, wide bid/ask spreads and extended trade settlement periods. The corporate loans in which the Fund invests are usually rated below investment grade.

• Credit Risk — Credit risk refers to the possibility that the issuer of a security will not be able to make payments of interest and principal when due. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Fund’s investment in that issuer.

• 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.

  Credit Default Swaps — Credit default swaps involve special risks in addition to those mentioned above because they are difficult to value, are highly susceptible to liquidity and credit risk, and generally pay a return to the party that has paid the premium only in the event of an actual default by the issuer of the underlying obligation (as opposed to a credit downgrade or other indication of financial difficulty). The protection “buyer” in a credit default contract may be obligated to pay the protection “seller” an up front payment or a periodic stream of payments over the term of the contract provided generally that no credit event on a reference obligation has occurred. If a credit event occurs, the seller generally must pay the buyer the “par value” (full notional value) of the swap in exchange for an equal face amount of deliverable obligations of the reference entity described in the swap, or the seller may be required to deliver the related net cash amount, if the swap is cash settled. The Fund may be either the buyer or seller in the transaction.

  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.

  To the extent derivatives are utilized to implement the Fund’s investment strategies, the transactions may involve the risks described below. For example, to the extent the Fund gains short exposure to a security through a derivative instrument, the Fund will be subject to risks associated with short sales that are described below.

• Dividend Risk — Because certain of the corporate loans held by the Fund will have floating or variable interest rates, the amounts of the Fund’s monthly distributions to its stockholders are expected to vary with fluctuations in market interest rates. Generally, when market interest rates fall, the amount of the distributions to stockholders will likewise decrease.

• 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.

• Event Risk — Event risk is the risk that corporate issuers may undergo restructurings, such as mergers, leveraged buyouts, takeovers, or similar events financed by increased debt. As a result of the added debt, the credit quality and market value of a company’s bonds and/or other debt securities may decline significantly.

• Extension Risk — When interest rates rise, certain obligations will be paid off by the obligor more slowly than anticipated, causing the value of these securities to fall.

• 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.  

— The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events have adversely affected the exchange rate of the Euro and may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments.

• High Portfolio Turnover Risk — The Fund may engage in active and frequent trading of its portfolio securities. High portfolio turnover (more than 100%) may result in increased transaction costs to the Fund, including brokerage commissions, dealer mark-ups and other transaction costs on the sale of the securities and on reinvestment in other securities. The sale of Fund portfolio securities may result in the realization and distribution to shareholders of higher capital gains or losses as compared to a fund with less active trading policies. Given the frequency of sales, such gain or loss will likely be short-term capital gain or loss and would 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.

• Interest Rate Risk — Interest rate risk is the risk that prices of bonds and other fixed income securities will increase as interest rates fall, and decrease as interest rates rise.

• Junk Bonds Risk — Although junk bonds generally pay higher rates of interest than investment grade bonds, junk bonds are speculative, high risk investments that may cause income and principal losses for the Fund.

• 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 Securities and Exchange Commission (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.

• Liquidity Risk — Liquidity risk exists when particular investments are difficult to purchase or sell. The Fund’s investments in illiquid securities may reduce the returns of the Fund because it may be difficult to sell the illiquid securities at an advantageous time or price. To the extent that the Fund’s principal investment strategies involve derivatives or securities with substantial market and/or credit risk, the Fund will tend to have the greatest exposure to liquidity risk. Liquid investments may become illiquid after purchase by the Fund, particularly during periods of market turmoil. Illiquid investments may be harder to value, especially in changing markets, and if the Fund is forced to sell these investments to meet redemption requests or for other cash needs, the Fund may suffer a loss. In addition, when there is illiquidity in the market for certain securities, the Fund, due to limitations on illiquid investments, may be subject to purchase and sale restrictions.

• 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.

• Mezzanine Securities Risk — Mezzanine securities carry the risk that the issuer will not be able to meet its obligations and that the equity securities purchased with the mezzanine investments may lose value.

• Mortgage- and Asset-Backed Securities Risks — Mortgage- and asset-backed securities represent interests in “pools” of mortgages or other assets, including consumer loans or receivables held in trust. Mortgage- and asset-backed securities are subject to credit, interest rate, prepayment and extension risks. These securities also are subject to risk of default on the underlying mortgage or asset, particularly during periods of economic downturn. Small movements in interest rates (both increases and decreases) may quickly and significantly reduce the value of certain mortgage-backed securities.

• Preferred Securities Risk — Preferred securities may pay fixed or adjustable rates of return. Preferred securities are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company's preferred securities generally pay dividends only after the company makes required payments to holders of its bonds and other debt. For this reason, the value of preferred securities will usually react more strongly than bonds and other debt to actual or perceived changes in the company's financial condition or prospects. Preferred securities of smaller companies may be more vulnerable to adverse developments than preferred stock of larger companies.

• Prepayment Risk — When interest rates fall, certain obligations will be paid off by the obligor more quickly than originally anticipated, and the Fund may have to invest the proceeds in securities with lower yields.

• Repurchase Agreements and Purchase and Sale Contracts Risk — If the other party to a repurchase agreement or purchase and sale contract defaults on its obligation under the agreement, the Fund may suffer delays and incur costs or lose money in exercising its rights under the agreement. If the seller fails to repurchase the security in either situation and the market value of the security declines, the Fund may lose money.

• Reverse Repurchase Agreements Risk — Reverse repurchase agreements involve the sale of securities held by the Fund with an agreement to repurchase the securities at an agreed-upon price, date and interest payment. Reverse repurchase agreements involve the risk that the other party may fail to return the securities in a timely manner or at all. The Fund could lose money if it is unable to recover the securities and the value of the collateral held by the Fund, including the value of the investments made with cash collateral, is less than the value of securities. These events could also trigger adverse tax consequences to the Fund.

• Second Lien Loans Risk — Second lien loans generally are subject to similar risks as those associated with investments in senior loans. Because second lien loans are subordinated or unsecured and thus lower in priority of payment to senior loans, they are subject to the additional risk that the cash flow of the borrower and property securing the loan or debt, if any, may be insufficient to meet scheduled payments after giving effect to the senior secured obligations of the borrower.

• Senior Loans Risk — There is less readily available, reliable information about most senior loans than is the case for many other types of securities. An economic downturn generally leads to a higher non-payment rate, and a senior loan may lose significant value before a default occurs. Moreover, any specific collateral used to secure a senior loan may decline in value or become illiquid, which would adversely affect the senior loan's value. No active trading market may exist for certain senior loans, which may impair the ability of the Fund to realize full value in the event of the need to sell a senior loan and which may make it difficult to value senior loans. Although senior loans in which the Fund will invest generally will be secured by specific collateral, there can be no assurance that liquidation of such collateral would satisfy the borrower's obligation in the event of non-payment of scheduled interest or principal or that such collateral could be readily liquidated. To the extent that a senior loan is collateralized by stock in the borrower or its subsidiaries, such stock may lose all of its value in the event of the bankruptcy of the borrower. Uncollateralized senior loans involve a greater risk of loss. The senior loans in which the Fund invests are usually rated below investment grade.

• 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 and Mid-Capitalization Company Risk — Companies with small or mid-size market capitalizations will normally have more limited product lines, markets and financial resources and will be dependent upon a more limited management group than larger capitalized companies. In addition, it is more difficult to get information on smaller companies, which tend to be less well known, have shorter operating histories, do not have significant ownership by large investors and are followed by relatively few securities analysts.

• Sovereign Debt Risk — Sovereign debt instruments are subject to the risk that a governmental entity may delay or refuse to pay interest or repay principal on its sovereign debt, due, for example, to cash flow problems, insufficient foreign currency reserves, political considerations, the relative size of the governmental entity's debt position in relation to the economy or the failure to put in place economic reforms required by the International Monetary Fund or other multilateral agencies.

• Structured Products Risk — Holders of structured products bear risks of the underlying investments, index or reference obligation and are subject to counterparty risk. The Fund may have the right to receive payments only from the structured product, and generally does not have direct rights against the issuer or the entity that sold the assets to be securitized. Certain structured products may be thinly traded or have a limited trading market. In addition to the general risks associated with debt securities discussed herein, structured products carry additional risks, including, but not limited to: the possibility that distributions from collateral securities will not be adequate to make interest or other payments; the quality of the collateral may decline in value or default; and the possibility that the structured products are subordinate to other classes. Structured notes are based upon the movement of one or more factors, including currency exchange rates, interest rates, referenced bonds and stock indices, and changes in interest rates and impact of these factors may cause significant price fluctuations. Additionally, changes in the reference instrument or security may cause the interest rate on the structured note to be reduced to zero.

• 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 0.75% 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] The Total Annual Fund Operating Expenses do not correlate to the ratios of expenses to average net assets given in the Fund's annual report, which do not include Acquired Fund Fees and Expenses.

[2] As described in the "Management of the Fund" section of the Fund's prospectus on pages 40-44, 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 1.40% (for Investor A Shares), 2.15% (for Investor C Shares) and 1.20% (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 Global Long/Short Credit Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Overview

Key Facts About BlackRock Global Long/Short Credit Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The investment objective of BlackRock Global Long/Short Credit Fund (the “Fund”), a series of BlackRock Funds^SM (the “Trust”), is to seek absolute total returns over a complete market cycle.

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 26 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-71 of the Fund’s statement of additional information (the “SAI”).

Shareholder Fees Caption [Text]

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Shareholder Fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

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

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

December 1, 2013

Portfolio Turnover [Heading]

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Portfolio Turnover:

Portfolio Turnover [Text Block]

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The Fund pays transaction costs, such as commissions, when it buys and sells securities (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 September 30, 2011 (commencement of operations) through July 31, 2012, the Fund’s portfolio turnover rate was 355% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

355.00%

Expenses Deferred Charges [Text Block]

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A contingent deferred sales charge (“CDSC”) of 0.75% 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]

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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

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

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The Total Annual Fund Operating Expenses do not correlate to the ratios of expenses to average net assets given in the Fund’s annual report, which do not include Acquired Fund Fees and Expenses.

Expense Example [Heading]

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Example:

Expense Example Narrative [Text Block]

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This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $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]

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

Strategy [Heading]

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Principal Investment Strategies of the Fund

Strategy Narrative [Text Block]

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The Fund seeks to provide absolute total returns over a complete market cycle through diversified long and short exposure to the global fixed income markets. A complete market cycle for fixed income funds such as the Fund is typically three to five years.

Under normal circumstances, the Fund invests at least 80% of its total assets in credit-related instruments, including, but not limited to, U.S. Government and agency securities, foreign government and supranational debt securities, corporate bonds, including bonds of companies principally engaged in the aircraft or air transportation industries, mortgage-related securities and asset-backed securities, collateralized debt and loan obligations, including bonds collateralized by aircraft and/or aircraft equipment, emerging market debt securities, preferred securities, structured products, mezzanine securities, senior secured floating rate and fixed rate loans or debt, second lien or other subordinated or unsecured floating rate and fixed rate loans or debt, convertible debt securities, and derivatives with similar economic characteristics. The Fund may invest in fixed, variable and floating rate instruments, including participations and assignments, of any duration or maturity.

Under normal circumstances, the Fund anticipates it will allocate a substantial amount (approximately 40% or more, unless market conditions are not deemed favorable by BlackRock, in which case the Fund would invest at least 30%) of its total assets in securities (or derivatives with similar economic characteristics) of (i) foreign government issuers, (ii) issuers organized or located outside the U.S., (iii) issuers whose securities primarily trade in a market located outside the U.S., or (iv) issuers doing a substantial amount of business outside the U.S., which the Fund considers to be companies that derive at least 50% of their revenue or profits from business outside the U.S. or have at least 50% of their sales or assets outside the U.S. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries).

The Fund may invest in credit-related instruments rated below investment grade or deemed equivalent by Fund management, which are commonly referred to as “junk bonds.”

Generally, the Fund’s average maturity is expected to be less than 6 years.

The Fund may invest in non-U.S. dollar denominated investments including investments denominated in European and Asian currencies and in other non-U.S. and emerging market currencies. The Fund’s investments in non-U.S. dollar based assets may be made on a currency hedged or unhedged basis.

The Fund may invest up to 20% of its total assets in equity instruments, including common stock, depositary receipts, rights, warrants and other instruments whose price is linked to the value of common stock. The Fund may hold long or short positions in equity instruments, and may invest in equity instruments of issuers of any market capitalization.

The Fund may also gain both long and short exposure to credit-related instruments by entering into a series of purchase and sale contracts or by investing in, among other instruments, swaps, including total return, credit default, index and interest rate swaps; options; forward contracts; futures contracts and options on futures contracts that provide long or short exposure to other credit obligations; credit-linked notes that provide long or short exposure to other credit obligations; repurchase agreements; reverse repurchase agreements; dollar rolls; exchange-traded funds and closed-end registered investment companies, which may be managed by BlackRock or one of its affiliates; and other similar transactions.

The Fund may engage in short sales for hedging purposes or to enhance total return. The Fund also may make short sales “against the box” without limitation. In this type of short sale, at the time of the sale, the Fund owns or has the immediate and unconditional right to acquire the identical security at no additional cost.

As part of its normal operations, the Fund may hold high quality money market securities and invest in money market funds, including affiliated money market funds, pending investments or when it expects to need cash to pay redeeming shareholders. The Fund also may invest in these securities in order to achieve its investment goal. Money market securities are short term securities consisting primarily of short term U.S. Government securities, U.S. Government agency securities, securities issued by U.S. Government sponsored enterprises and U.S. Government instrumentalities, bank obligations, commercial paper, including asset backed commercial paper, corporate notes and repurchase agreements.

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

The Fund may borrow from banks for investment purposes.

Risk [Heading]

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Principal Risks of Investing in the Fund

Risk Narrative [Text Block]

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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.

• Air Transportation Industry Risks — The air transportation industry can be significantly affected by competition within the industry, domestic and foreign economies, government regulation, labor relations, and the price of fuel. Airline deregulation has substantially diminished the government’s role in the air transport industry while promoting an increased level of competition. However, regulations and policies of various domestic and foreign governments can still affect the profitability of individual carriers as well as the entire industry.

• Borrowing Risk — Borrowing may exaggerate changes in the net asset value of Fund shares and in the return on the Fund’s portfolio. Borrowing will cost the Fund interest expense and other fees. The costs of borrowing may reduce the Fund’s return. Borrowing may cause the Fund to liquidate positions when it may not be advantageous to do so to satisfy its obligations.

• Collateralized Debt Obligations Risks — Collateralized debt obligations are subject to credit, interest rate, valuation, prepayment and extension risks. These securities also are subject to risk of default on the underlying asset, particularly during periods of economic downturn.

• 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 risk as apply to the underlying common stock.

• Corporate Loans Risk — Commercial banks and other financial institutions or institutional investors make corporate loans to companies that need capital to grow or restructure. Borrowers generally pay interest on corporate loans at rates that change in response to changes in market interest rates such as the London Interbank Offered Rate (“LIBOR”) or the prime rates of U.S. banks. As a result, the value of corporate loan investments is generally less exposed to the adverse effects of shifts in market interest rates than investments that pay a fixed rate of interest. The market for corporate loans may be subject to irregular trading activity, wide bid/ask spreads and extended trade settlement periods. The corporate loans in which the Fund invests are usually rated below investment grade.

• Credit Risk — Credit risk refers to the possibility that the issuer of a security will not be able to make payments of interest and principal when due. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Fund’s investment in that issuer.

• 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.

  Credit Default Swaps — Credit default swaps involve special risks in addition to those mentioned above because they are difficult to value, are highly susceptible to liquidity and credit risk, and generally pay a return to the party that has paid the premium only in the event of an actual default by the issuer of the underlying obligation (as opposed to a credit downgrade or other indication of financial difficulty). The protection “buyer” in a credit default contract may be obligated to pay the protection “seller” an up front payment or a periodic stream of payments over the term of the contract provided generally that no credit event on a reference obligation has occurred. If a credit event occurs, the seller generally must pay the buyer the “par value” (full notional value) of the swap in exchange for an equal face amount of deliverable obligations of the reference entity described in the swap, or the seller may be required to deliver the related net cash amount, if the swap is cash settled. The Fund may be either the buyer or seller in the transaction.

  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.

  To the extent derivatives are utilized to implement the Fund’s investment strategies, the transactions may involve the risks described below. For example, to the extent the Fund gains short exposure to a security through a derivative instrument, the Fund will be subject to risks associated with short sales that are described below.

• Dividend Risk — Because certain of the corporate loans held by the Fund will have floating or variable interest rates, the amounts of the Fund’s monthly distributions to its stockholders are expected to vary with fluctuations in market interest rates. Generally, when market interest rates fall, the amount of the distributions to stockholders will likewise decrease.

• 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.

• Event Risk — Event risk is the risk that corporate issuers may undergo restructurings, such as mergers, leveraged buyouts, takeovers, or similar events financed by increased debt. As a result of the added debt, the credit quality and market value of a company’s bonds and/or other debt securities may decline significantly.

• Extension Risk — When interest rates rise, certain obligations will be paid off by the obligor more slowly than anticipated, causing the value of these securities to fall.

• 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.  

— The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events have adversely affected the exchange rate of the Euro and may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments.

• High Portfolio Turnover Risk — The Fund may engage in active and frequent trading of its portfolio securities. High portfolio turnover (more than 100%) may result in increased transaction costs to the Fund, including brokerage commissions, dealer mark-ups and other transaction costs on the sale of the securities and on reinvestment in other securities. The sale of Fund portfolio securities may result in the realization and distribution to shareholders of higher capital gains or losses as compared to a fund with less active trading policies. Given the frequency of sales, such gain or loss will likely be short-term capital gain or loss and would 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.

• Interest Rate Risk — Interest rate risk is the risk that prices of bonds and other fixed income securities will increase as interest rates fall, and decrease as interest rates rise.

• Junk Bonds Risk — Although junk bonds generally pay higher rates of interest than investment grade bonds, junk bonds are speculative, high risk investments that may cause income and principal losses for the Fund.

• 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 Securities and Exchange Commission (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.

• Liquidity Risk — Liquidity risk exists when particular investments are difficult to purchase or sell. The Fund’s investments in illiquid securities may reduce the returns of the Fund because it may be difficult to sell the illiquid securities at an advantageous time or price. To the extent that the Fund’s principal investment strategies involve derivatives or securities with substantial market and/or credit risk, the Fund will tend to have the greatest exposure to liquidity risk. Liquid investments may become illiquid after purchase by the Fund, particularly during periods of market turmoil. Illiquid investments may be harder to value, especially in changing markets, and if the Fund is forced to sell these investments to meet redemption requests or for other cash needs, the Fund may suffer a loss. In addition, when there is illiquidity in the market for certain securities, the Fund, due to limitations on illiquid investments, may be subject to purchase and sale restrictions.

• 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.

• Mezzanine Securities Risk — Mezzanine securities carry the risk that the issuer will not be able to meet its obligations and that the equity securities purchased with the mezzanine investments may lose value.

• Mortgage- and Asset-Backed Securities Risks — Mortgage- and asset-backed securities represent interests in “pools” of mortgages or other assets, including consumer loans or receivables held in trust. Mortgage- and asset-backed securities are subject to credit, interest rate, prepayment and extension risks. These securities also are subject to risk of default on the underlying mortgage or asset, particularly during periods of economic downturn. Small movements in interest rates (both increases and decreases) may quickly and significantly reduce the value of certain mortgage-backed securities.

• Preferred Securities Risk — Preferred securities may pay fixed or adjustable rates of return. Preferred securities are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company's preferred securities generally pay dividends only after the company makes required payments to holders of its bonds and other debt. For this reason, the value of preferred securities will usually react more strongly than bonds and other debt to actual or perceived changes in the company's financial condition or prospects. Preferred securities of smaller companies may be more vulnerable to adverse developments than preferred stock of larger companies.

• Prepayment Risk — When interest rates fall, certain obligations will be paid off by the obligor more quickly than originally anticipated, and the Fund may have to invest the proceeds in securities with lower yields.

• Repurchase Agreements and Purchase and Sale Contracts Risk — If the other party to a repurchase agreement or purchase and sale contract defaults on its obligation under the agreement, the Fund may suffer delays and incur costs or lose money in exercising its rights under the agreement. If the seller fails to repurchase the security in either situation and the market value of the security declines, the Fund may lose money.

• Reverse Repurchase Agreements Risk — Reverse repurchase agreements involve the sale of securities held by the Fund with an agreement to repurchase the securities at an agreed-upon price, date and interest payment. Reverse repurchase agreements involve the risk that the other party may fail to return the securities in a timely manner or at all. The Fund could lose money if it is unable to recover the securities and the value of the collateral held by the Fund, including the value of the investments made with cash collateral, is less than the value of securities. These events could also trigger adverse tax consequences to the Fund.

• Second Lien Loans Risk — Second lien loans generally are subject to similar risks as those associated with investments in senior loans. Because second lien loans are subordinated or unsecured and thus lower in priority of payment to senior loans, they are subject to the additional risk that the cash flow of the borrower and property securing the loan or debt, if any, may be insufficient to meet scheduled payments after giving effect to the senior secured obligations of the borrower.

• Senior Loans Risk — There is less readily available, reliable information about most senior loans than is the case for many other types of securities. An economic downturn generally leads to a higher non-payment rate, and a senior loan may lose significant value before a default occurs. Moreover, any specific collateral used to secure a senior loan may decline in value or become illiquid, which would adversely affect the senior loan's value. No active trading market may exist for certain senior loans, which may impair the ability of the Fund to realize full value in the event of the need to sell a senior loan and which may make it difficult to value senior loans. Although senior loans in which the Fund will invest generally will be secured by specific collateral, there can be no assurance that liquidation of such collateral would satisfy the borrower's obligation in the event of non-payment of scheduled interest or principal or that such collateral could be readily liquidated. To the extent that a senior loan is collateralized by stock in the borrower or its subsidiaries, such stock may lose all of its value in the event of the bankruptcy of the borrower. Uncollateralized senior loans involve a greater risk of loss. The senior loans in which the Fund invests are usually rated below investment grade.

• 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 and Mid-Capitalization Company Risk — Companies with small or mid-size market capitalizations will normally have more limited product lines, markets and financial resources and will be dependent upon a more limited management group than larger capitalized companies. In addition, it is more difficult to get information on smaller companies, which tend to be less well known, have shorter operating histories, do not have significant ownership by large investors and are followed by relatively few securities analysts.

• Sovereign Debt Risk — Sovereign debt instruments are subject to the risk that a governmental entity may delay or refuse to pay interest or repay principal on its sovereign debt, due, for example, to cash flow problems, insufficient foreign currency reserves, political considerations, the relative size of the governmental entity's debt position in relation to the economy or the failure to put in place economic reforms required by the International Monetary Fund or other multilateral agencies.

• Structured Products Risk — Holders of structured products bear risks of the underlying investments, index or reference obligation and are subject to counterparty risk. The Fund may have the right to receive payments only from the structured product, and generally does not have direct rights against the issuer or the entity that sold the assets to be securitized. Certain structured products may be thinly traded or have a limited trading market. In addition to the general risks associated with debt securities discussed herein, structured products carry additional risks, including, but not limited to: the possibility that distributions from collateral securities will not be adequate to make interest or other payments; the quality of the collateral may decline in value or default; and the possibility that the structured products are subordinate to other classes. Structured notes are based upon the movement of one or more factors, including currency exchange rates, interest rates, referenced bonds and stock indices, and changes in interest rates and impact of these factors may cause significant price fluctuations. Additionally, changes in the reference instrument or security may cause the interest rate on the structured note to be reduced to zero.

• 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]

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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]

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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]

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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 Global Long/Short Credit Fund | Investor A Shares

Risk/Return:

rr_RiskReturnAbstract

Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.00%

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

0.95%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses

rr_OtherExpensesOverAssets

0.73%

Interest Expense

rr_Component1OtherExpensesOverAssets

0.26%

Miscellaneous Other Expenses

rr_Component2OtherExpensesOverAssets

0.47%

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.11%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.04%

^[2]

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.27%)

^[3]

Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

1.77%

^[3]

1 Year

rr_ExpenseExampleYear01

573

3 Years

rr_ExpenseExampleYear03

989

5 Years

rr_ExpenseExampleYear05

1,430

10 Years

rr_ExpenseExampleYear10

2,653

BlackRock Global Long/Short Credit 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%

^[4]

Management Fee

rr_ManagementFeesOverAssets

0.95%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other Expenses

rr_OtherExpensesOverAssets

0.71%

Interest Expense

rr_Component1OtherExpensesOverAssets

0.26%

Miscellaneous Other Expenses

rr_Component2OtherExpensesOverAssets

0.45%

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.11%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

2.77%

^[2]

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.25%)

^[3]

Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

2.52%

^[3]

1 Year

rr_ExpenseExampleYear01

355

3 Years

rr_ExpenseExampleYear03

836

5 Years

rr_ExpenseExampleYear05

1,442

10 Years

rr_ExpenseExampleYear10

3,081

1 Year

rr_ExpenseExampleNoRedemptionYear01

255

3 Years

rr_ExpenseExampleNoRedemptionYear03

836

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,442

10 Years

rr_ExpenseExampleNoRedemptionYear10

3,081

BlackRock Global Long/Short Credit 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

0.95%

Distribution and/or Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.78%

Interest Expense

rr_Component1OtherExpensesOverAssets

0.26%

Miscellaneous Other Expenses

rr_Component2OtherExpensesOverAssets

0.52%

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.11%

^[2]

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.84%

^[2]

Fee Waivers and/or Expense Reimbursements

rr_FeeWaiverOrReimbursementOverAssets

(0.27%)

^[3]

Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements

rr_NetExpensesOverAssets

1.57%

^[3]

1 Year

rr_ExpenseExampleYear01

160

3 Years

rr_ExpenseExampleYear03

552

5 Years

rr_ExpenseExampleYear05

970

10 Years

rr_ExpenseExampleYear10

2,136

[1] A contingent deferred sales charge ("CDSC") of 0.75% 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 Total Annual Fund Operating Expenses do not correlate to the ratios of expenses to average net assets given in the Fund's annual report, which do not include Acquired Fund Fees and Expenses.

[3] As described in the "Management of the Fund" section of the Fund's prospectus on pages 40-44, 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 1.40% (for Investor A Shares), 2.15% (for Investor C Shares) and 1.20% (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.

[4] 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