POS EX

As filed with the Securities and Exchange Commission on September 14, 2007

Securities Act File No. 333-133761

U.S. SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-14

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

o Pre-Effective Amendment No.

x Post-Effective Amendment No. 1

(Check appropriate box or boxes)

BLACKROCK FUNDS ^SM

(Exact Name of Registrant as Specified in Agreement and Declaration of Trust)

Bellevue Park Corporate Center

100 Bellevue Parkway

Wilmington, DE 19809

(Address of Principal Executive Offices)

Telephone Number: (888) 825-2257

(Area Code and Telephone Number)

Brian Kindelan, Esq.

BlackRock Advisors, Inc.

Bellevue Park Corporate Center

100 Bellevue Parkway

Wilmington, DE19809

(Name and Address of Agent for Service)

Copies to:

Richard T. Prins, Esq.	Sarah E. Cogan, Esq.	Frank P. Bruno, Esq.
Skadden, Arps, Slate, Meagher & Flom LLP	Simpson Thacher & Bartlett LLP	Sidley Austin LLP
4 Times Square	425 Lexington Avenue	787 Seventh Avenue
New York, New York 10036-6522	New York, New York 10017	New York, New York 10019-6018

EXPLANATORY NOTE

                The Joint Proxy Statement/Prospectus in the form filed on June 23, 2006 pursuant to Rule 497 of the General Rules and Regulations under the Securities Act of 1933, as amended, and the Statement of Additional Information included in Pre-Effective Amendment No. 2 to the Registration Statement (File No. 333-133761) in the form filed on June 19, 2006 are incorporated herein by reference.

                This amendment is being filed in order to file, as Exhibit 12 to this Registration Statement, the tax opinion of Skadden, Arps, Slate, Meagher & Flom LLP, tax counsel for BlackRock Funds (the “Registrant”).

PART C

OTHER INFORMATION

Item 15. Indemnification

There has been no change in the information set forth in Item 15 of the Registration Statement of the Registrant on Form N-14 (File No. 333-133761) under the Securities Act of 1933, as amended, as filed with the Securities and Exchange Commission on June 19, 2006, which information is incorporated herein by reference.

C-1

Item 16. Exhibits

Ex. Number	Description
(1)(a)	Declaration of Trust of BlackRock Funds dated December 22, 1988 is incorporated herein by reference to Exhibit (1)(a) of Post-Effective Amendment No. 33 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 27, 1998
(b)	Amendment No. 1 to Declaration of Trust dated May 4, 1989 is incorporated herein by reference to Exhibit (1)(b) of Post-Effective Amendment No. 33 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 27, 1998
(c)	Amendment No. 2 to the Declaration of Trust dated December 23, 1993 is incorporated herein by reference to Exhibit (1)(c) of Post-Effective Amendment No. 33 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 27, 1998
(d)	Amendment No. 3 to the Declaration of Trust dated January 5, 1996 is incorporated by reference to Exhibit 1(d) of Post-Effective Amendment No. 23 to BlackRock Funds’ Registration Statement on Form N-1A (No. 33-26305) filed on October 18, 1996
(e)	Amendment No. 4 to the Declaration of Trust dated December 23, 1997 is incorporated herein by reference to Exhibit (1)(e) of Post-Effective Amendment No. 33 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 27, 1998
(2)	Amended and Restated Code of Regulations of BlackRock Funds is incorporated herein by reference to Exhibit 2(a) of Post-Effective Amendment No. 42 to BlackRock Funds’ Registration Statement on Form N-1A filed on June 11, 1999
(3)	None
(4)	Form of Agreement and Plan of Reorganization is incorporated herein by reference to Appendix B of the Joint Proxy Statement/Prospectus in the form filed on June 23, 2006 pursuant to Rule 497 of the General Rules and Regulations under the Securities Act of 1933, as amended (File No. 333-133761)
(5)	Sections V, VIII and IX of BlackRock Funds’ Declaration of Trust dated December 22, 1988 are incorporated herein by reference to Exhibit (1)(a) of Post-Effective Amendment No. 33 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 27, 1998; Article II of BlackRock Funds’ Amended and Restated Code of Regulations is incorporated herein by reference to Exhibit (2)(a) of Post-Effective Amendment No. 42 to BlackRock Funds’ Registration Statement on Form N-1A filed on June 11, 1999
(6)(a)	Investment Advisory Agreement between BlackRock Funds and BlackRock Advisors, Inc. relating to all then-existing Portfolios except the Multi-Sector Mortgage Securities Portfolio III and Index Equity Portfolio is incorporated herein by reference to Exhibit (5)(a) of Post-Effective Amendment No. 21 to BlackRock Funds’ Registration Statement on Form N-1A filed on May 30, 1996
(b)	Form of Amendment No. 1 to Investment Advisory Agreement between BlackRock Funds and BlackRock Advisors, Inc. dated as of May 8, 2002 is incorporated herein by

C-2

	reference to Exhibit 4(ee) of Post-Effective Amendment No. 68 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 28, 2003
(c)	Form of Addendum No. 4 to Investment Advisory Agreement between BlackRock Funds and BlackRock Advisors, Inc. with respect to the High Yield Bond Portfolio is incorporated herein by reference to Exhibit 5(s) of Post-Effective Amendment No. 37 to BlackRock Funds’ Registration Statement on Form N-1A filed on August 7, 1998
(d)	Form of Sub-Advisory Agreement between BlackRock Advisors, Inc. and BlackRock Financial Management, Inc. with respect to the High Yield Bond Portfolio is incorporated herein by reference to Exhibit 5(t) of Post-Effective Amendment No. 37 to BlackRock Funds’ Registration Statement on Form N-1A filed on August 7, 1998
(7)(a)	Distribution Agreement between BlackRock Funds and BlackRock Distributors, Inc. dated as of January 2, 2001 is incorporated herein by reference to Exhibit 5(a) of Post-Effective Amendment No. 59 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 29, 2001
(b)	Form of Appendix A to Distribution Agreement between BlackRock Funds and BlackRock Distributors, Inc. is incorporated herein by reference to Exhibit 5(b) of Post-Effective Amendment No. 94 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 27, 2006
(c)	Form of Cooperation Agreement among BlackRock Funds, BlackRock Advisors, Inc. and UBS AG is incorporated herein by reference to Exhibit 5(c) of Post-Effective Amendment No. 91 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 31, 2005
(8)	None
(9)(a)	Amended and Restated Custodian Agreement dated February 10, 2004 between BlackRock Funds and PFPC is incorporated herein by reference to Exhibit 7(a) of Post-Effective Amendment No. 86 to BlackRock Funds’ Registration Statement on Form N-1A filed on November 3, 2004
(b)	Sub-Custodian Agreement dated April 27, 1992 among BlackRock Funds, PNC Bank, National Association and The Chase Manhattan Bank is incorporated herein by reference to Exhibit (8)(e) of Post-Effective Amendment No. 34 to BlackRock Funds’ Registration Statement on Form N-1A filed on February 13, 1998
(c)	Global Custody Agreement between Barclays Bank PLC and PNC Bank, National Association dated October 28, 1992 is incorporated herein by reference to Exhibit (8)(f) of Post-Effective Amendment No. 33 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 27, 1998
(d)	Custodian Agreement between State Street Bank and Trust Company and PNC Bank, National Association dated June 13, 1983 is incorporated herein by reference to Exhibit (8)(g) of Post-Effective Amendment No. 34 to BlackRock Funds’ Registration Statement on Form N-1A filed on February 13, 1998
(e)	Amendment No. 1 to Custodian Agreement between State Street Bank and Trust Company and PNC Bank, National Association dated November 21, 1989 is incorporated herein by reference to Exhibit (8)(h) of Post-Effective Amendment No. 34 to BlackRock Funds’ Registration Statement on Form N-1A filed on February 13, 1998
(f)	Subcustodial Services Agreement dated January 10, 1996 between PNC Bank, National Association and Citibank, N.A. is incorporated herein by reference to Exhibit 8(j) of Post-Effective Amendment No. 27 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 28, 1997
(10)(a)	Amended and Restated Distribution and Service Plan dated September 10, 2004 of BlackRock Funds for Service, Series A Investor, Series B Investor, Series C Investor, Institutional, HL and BlackRock Shares is incorporated herein by reference to Exhibit 13(a) of Post-Effective

C-3

	Amendment No. 86 to BlackRock Funds’ Registration Statement on Form N-1A filed on November 3, 2004
(b)	Form of Appendix A to Amended and Restated Distribution and Service Plan is incorporated herein by reference to Exhibit 13(b) of Post-Effective Amendment No. 94 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 27, 2006
(c)	Amended and Restated Plan Pursuant to Rule 18f-3 for Operation of a Multi-Class Distribution System dated September 10, 2004 of BlackRock Funds is incorporated herein by reference to Exhibit 14(a) of Post-Effective Amendment No. 86 to BlackRock Funds’ Registration Statement on Form N-1A filed on November 3, 2004

(11) Opinion and Consent of Skadden, Arps, Slate, Meagher & Flom LLP, is incorporated herein by reference to Exhibit 11 of Pre-Effective Amendment No. 1 to BlackRock Funds' Registration Statement on Form N-14 filed on June 16, 2006

(12)	Opinion of Skadden, Arps, Slate, Meagher & Flom LLP regarding certain tax matters, filed herewith
(13)(a)	Amended and Restated Administration Agreement dated February 10, 2004 among BlackRock Funds, BlackRock Advisors, Inc. and PFPC Inc. is incorporated herein by reference to Exhibit 8(a) of Post-Effective Amendment No. 86 to BlackRock Funds’ Registration Statement on Form N-1A filed on November 3, 2004
(b)	Form of Appendix A to the Amended and Restated Administration Agreement among BlackRock Funds, BlackRock Advisors, Inc. and PFPC Inc. is incorporated herein by reference to Exhibit 8(b) of Post-Effective Amendment No. 94 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 27, 2006
(c)	Amended and Restated Transfer Agency Agreement dated February 10, 2004 between BlackRock Funds and PFPC Inc. is incorporated herein by reference to Exhibit 8(c) of Post-Effective Amendment No. 86 to BlackRock Funds’ Registration Statement on Form N-1A filed on November 3, 2004
(d)	Form of Exhibit A to the Amended and Restated Transfer Agency Agreement between BlackRock Funds and PFPC Inc. is incorporated herein by reference to Exhibit 8(h) of Post-Effective Amendment No. 94 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 27, 2006
(e)	Share Acquisition Agreement dated April 29, 1998 by and among BlackRock Funds and PNC Bank, National Association and PNC Bank, Delaware, respectively, each as trustee for certain of the common trust funds listed therein is incorporated herein by reference to Exhibit 9(l) of Post-Effective Amendment No. 36 to BlackRock Funds’ Registration Statement on Form N-1A filed on April 29, 1998
(f)	Schedule A to Expense Limitation Agreement is incorporated herein by reference to Exhibit 8(l) of Post-Effective Amendment No. 94 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 27, 2006
(g)	Form of Shareholders’ Administrative Services Agreement between BlackRock Funds and BlackRock Advisors, Inc. is incorporated herein by reference to Exhibit 8(p) of Post-Effective Amendment No. 91 to BlackRock Funds’ Registration Statement on Form N-1A filed on January 31, 2005
(14)(a)	Consent of independent auditors of the BlackRock Fund is incorporated herein by reference to Exhibit 14(a) of Pre-Effective Amendment No. 2 to BlackRock Funds' Registration Statement on Form N-14 (File No. 333-133761) filed on June 19, 2006
(b)	Consent of independent auditors of the ML Fund is incorporated herein by reference to Exhibit 14(b) of Pre-Effective Amendment No. 2 to BlackRock Funds' Registration Statement on Form N-14 (File No. 333-133761) filed on June 19, 2006

C-4

(15)	None
(16)(a)	Power of Attorney of David R. Wilmerding, Jr. dated June 12, 2006 is incorporated herein by reference to Exhibit 16(a) of Pre-Effective Amendment No. 1 to BlackRock Funds' Registration Statement on Form N-14 filed on June 16, 2006
(b)	Power of Attorney of Robert M. Hernandez dated June 12, 2006 is incorporated herein by reference to Exhibit 16(b) of Pre-Effective Amendment No. 1 to BlackRock Funds' Registration Statement on Form N-14 filed on June 16, 2006
(c)	Power of Attorney of Laurence D. Fink dated June 12, 2006 is incorporated herein by reference to Exhibit 16(c) of Pre-Effective Amendment No. 1 to BlackRock Funds' Registration Statement on Form N-14 filed on June 16, 2006
(d)	Power of Attorney of Stuart E. Eizenstat dated June 14, 2006 is incorporated herein by reference to Exhibit 16(d) of Pre-Effective Amendment No. 1 to BlackRock Funds' Registration Statement on Form N-14 filed on June 16, 2006
(e)	Power of Attorney of Dr. Matina Horner dated June 12, 2006 is incorporated herein by reference to Exhibit 16(e) of Pre-Effective Amendment No. 1 to BlackRock Funds' Registration Statement on Form N-14 filed on June 16, 2006
(f)	Power of Attorney of Bruce R. Bond dated June 12, 2006 is incorporated herein by reference to Exhibit 16(f) of Pre-Effective Amendment No. 1 to BlackRock Funds' Registration Statement on Form N-14 filed on June 16, 2006
(g)	Power of Attorney of Richard S. Davis dated June 12, 2006 is incorporated herein by reference to Exhibit 16(g) of Pre-Effective Amendment No. 1 to BlackRock Funds' Registration Statement on Form N-14 filed on June 16, 2006
(h)	Power of Attorney of Toby Rosenblatt dated June 12, 2006 is incorporated herein by reference to Exhibit 16(i) of Pre-Effective Amendment No. 1 to BlackRock Funds' Registration Statement on Form N-14 filed on June 16, 2006
(17)	Form of Proxy Ballot, is incorporated herein by reference to Exhibit 17 of Pre-Effective Amendment No. 1 to BlackRock Funds' Registration Statement on Form N-14 filed on June 16, 2006

Item 17. Undertakings

(1) The undersigned registrant agrees that prior to any public reoffering of the securities registered through the use of a prospectus which is a part of this registration statement by any person or party who is deemed to be an underwriter within the meaning of Rule 145(c) of the 1933 Act, the reoffering prospectus will contain the information called for by the applicable registration form for reofferings by persons who may be deemed underwriters, in addition to the information called for by other items of the applicable form.

C-5

(2) The undersigned registrant agrees that every prospectus that is filed under paragraph (1) above will be filed as a part of an amendment to the registration statement and will not be used until the amendment is effective, and that, in determining any liability under the 1933 Act, each post-effective amendment shall be deemed to be a new registration statement for the securities offered therein, and the offering of the securities at that time shall be deemed to be the initial bona fide offering of them.

C-6

SIGNATURES

As required by the Securities Act of 1933, as amended, this registration statement has been signed on behalf of the registrant in the City of New York and State of New York, on the 14th day of September, 2007.

BLACKROCK FUNDS^SM

By:

/s/ Donald C. Burke

Donald C. Burke

President

(Principal Executive Officer)

By:

/s/ Jay Fife

Jay Fife

Treasurer

(Principal Financial Officer)

Pursuant to the requirements of the Securities Act of 1933, as amended, this registration statement has been signed below by the following persons in the capacities indicated on the dates indicated.

Signature	Title	Date
/s/ *BRUCE R. BOND	Trustee	September 14, 2007
(Bruce R. Bond)
/s/ *RICHARD S. DAVIS	Trustee	September 14, 2007
(Richard S. Davis)
/s/ *STUART E. EIZENSTAT	Trustee	September 14, 2007
(Stuart E. Eizenstat)
/s/ *LAURENCE D. FINK	Trustee	September 14, 2007
(Laurence D. Fink)
/s/ *ROBERT M. HERNANDEZ	Trustee	September 14, 2007
(Robert M. Hernandez)
/s/ *DR. MATINA HORNER	Trustee	September 14, 2007
(Dr. Matina Horner)
/s/ *TOBY ROSENBLATT	Trustee	September 14, 2007
(Toby Rosenblatt)
/s/ *DAVID R. WILMERDING, JR.	Trustee and Chairman of the Board	September 14, 2007
(David R. Wilmerding, Jr.)

*By:
/s/ Anne Ackerley	September 14, 2007
Anne Ackerley, Attorney-in-fact

C-7

SCHEDULE OF EXHIBITS TO FORM N-14

Ex. Number	Description
(12)	Opinion of Skadden, Arps, Slate, Meagher & Flom LLP regarding certain tax matters

EX-99.(12)

Exhibit (12)

October 16, 2006

Master U.S. High Yield Trust

800 Scudders Mill Road

Plainsboro, New Jersey 08536

BlackRock Funds^SM

301 Bellevue Parkway

Wilmington, Delaware 19809

Ladies and Gentlemen:

We have acted as special counsel to BlackRock Funds^SM, a voluntary association with transferable shares organized and existing under the laws of the Commonwealth of Massachusetts, on behalf of its series listed on Schedule A (collectively, the “Acquiring Funds”) in connection with the acquisition by the Acquiring Funds of substantially all of the assets and the assumption of substantially all of the liabilities of the Merrill Lynch funds listed on Schedule B (collectively, the “Target Funds”), in exchange for newly-issued shares of the Acquiring Funds. BlackRock Funds^SM and the Target Funds are registered under the Investment Company Act of 1940, as amended.

This opinion is being furnished specifically in connection with (i) the acquisition by BlackRock High Yield Bond Portfolio (the “BlackRock Fund”), a separate series of BlackRock Funds^SM, of all of the assets of BlackRock U.S. High Yield Fund, Inc., formerly named Merrill Lynch U.S. High Yield Fund, Inc. (the “ML Fund”), a registered investment company and a Maryland Corporation that, as a “feeder fund”, invests all of its assets in the Master U.S. High Yield Trust, a registered investment company and a Delaware statutory trust, solely in exchange for Investor A, Investor B1, Investor C1, R and Institutional shares of beneficial interest of the BlackRock Fund (the “Shares”), each with a par value of $0.001 per Share, and the assumption by the BlackRock Fund of the Stated Liabilities of the ML Fund and (ii) the subsequent liquidation of the ML Fund (collectively, the “Reorganization”). The Reorganization will be consummated pursuant to the Agreement and Plan of Reorganization, made as of  June 19, 2006 (the “Agreement”). This opinion is being furnished pursuant to Section 8.6 of the Agreement. Any terms not defined herein shall have the meanings assigned to them in the Agreement.

In connection with our opinion, we have reviewed originals or copies, certified or otherwise identified to our satisfaction, of the Agreement, the Registration Statement and such other documents, certificates and records as we have deemed necessary or appropriate as a basis for the opinion set forth below. We have assumed that

the Reorganization will be consummated in accordance with the Agreement, the Registration Statement and such other documents, certificates and records.  For purposes of our opinion, we have assumed the legal capacity of all natural persons, the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as certified, conformed or photostatic copies and the authenticity of the originals of such latter documents. We have assumed that such documents, certificates and records are duly authorized, valid and enforceable.

In rendering our opinion, we have also relied upon statements and representations of officers and other representatives of the BlackRock Fund and the ML Fund and have assumed that such statements and representations are and will continue to be correct without regard to any qualification as to knowledge or belief.  Our opinion is based on the Code, Treasury regulations, judicial authorities, published positions of the Internal Revenue Service (the “IRS”) and such other authorities as we have considered relevant, all as in effect as of the date of this opinion and all of which are subject to change or differing interpretations (possibly with retroactive effect). A change in the authorities upon which our opinion is based could affect our conclusions. An opinion of counsel is not binding on the IRS or any court. No assurance can be given that the IRS would not assert, or that a court would not sustain, a position contrary to this opinion.

Based upon and subject to the foregoing, we are of the opinion that, for United States federal income tax purposes,

a)the Reorganization will be treated as a “reorganization” within the meaning of Section 368(a) of the Code and the BlackRock Fund and the ML Fund will each be a “party to a reorganization” within the meaning of Section 368(b) of the Code;

b)no gain or loss will be recognized by the BlackRock Fund upon the receipt of all of the assets of the ML Fund solely in exchange for the Shares and the assumption by the BlackRock Fund of the Stated Liabilities of the ML Fund;

c)no gain or loss will be recognized by the ML Fund upon the transfer of all of its assets to the BlackRock Fund solely in exchange for the Shares and the assumption by the BlackRock Fund of the Stated Liabilities of the ML Fund or upon the distribution (whether actual or constructive) of the Shares to shareholders of the ML Fund in exchange for such shareholders’ shares of the ML Fund in liquidation of the ML Fund;

d)no gain or loss will be recognized by the shareholders of the ML Fund upon the exchange of their ML Fund shares solely for the Shares pursuant to the Reorganization;

2

e)the aggregate tax basis of the Shares received by each shareholder of ML Fund pursuant to the Reorganization will be the same as the aggregate tax basis of the ML Fund shares exchanged therefor by such shareholder;

f)the holding period of the Shares received by each shareholder of the ML Fund pursuant to the Reorganization will include the period during which the ML Fund shares exchanged therefor were held by such shareholder, provided such ML Fund shares are held as capital assets at the time of the Reorganization;

g)the tax basis of the assets acquired by the BlackRock Fund will be the same as the tax basis of such assets to the ML Fund immediately before the Reorganization; and

h)the holding period of the assets acquired by the BlackRock Fund will include the period during which those assets were held by the ML Fund.

Except as set forth above, we express no other opinion. This opinion is delivered to you solely for your benefit in connection with the Reorganization and cannot be relied upon by anyone else without our prior written consent. This opinion is expressed as of the date hereof and we disclaim any undertaking to advise you of any subsequent changes in respect of the matters stated or assumed herein or any changes in applicable law.

Very truly yours,

/s/ Skadden, Arps, Slate, Meagher & Flom LLP

3

SCHEDULE A

BLACKROCK FUNDS

BlackRock High Yield Bond Portfolio

BlackRock Inflation Protected Bond Portfolio

BlackRock Government Income Portfolio

BlackRock Low Duration Bond Portfolio

4

SCHEDULE B

MERRILL LYNCH FUNDS

BlackRock U.S. High Yield Fund, Inc., formerly named Merrill Lynch U.S. High Yield Fund, Inc.

Inflation Protected Fund, formerly named Merrill Lynch Inflation Protected Fund

BlackRock U.S. Government Fund, formerly named Merrill Lynch U.S. Government Fund

BlackRock Short Term U.S. Government Fund, Inc., formerly named Merrill Lynch Short Term U.S. Government Fund, Inc.

5