1933 Act File No. 002-62797
1940 Act File No. 811-02871

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM N-1A
REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	x
Pre-Effective Amendment No.	o
Post-Effective Amendment No. 50	x
and/or
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	x
Post-Effective Amendment No. 49	x

LORD ABBETT DEVELOPING GROWTH FUND, INC.

(Exact Name of Registrant as Specified in Charter)

	90 Hudson Street, Jersey City, New Jersey	07302-3973
	(Address of Principal Executive Office)	(Zip Code)
Registrant’s Telephone Number, including Area Code: (800) 201-6984

Thomas R. Phillips, Esq.

Vice President and Assistant Secretary

90 Hudson Street, Jersey City, New Jersey 07302-3973

(Name and Address of Agent for Service)

It is proposed that this filing will become effective (check appropriate box)
x	immediately upon filing pursuant to paragraph (b)
o	on (date) pursuant to paragraph (b)
o	60 days after filing pursuant to paragraph (a)(1)
o	on (date) pursuant to paragraph (a)(1)
o	75 days after filing pursuant to paragraph (a)(2)
o	on (date) pursuant to paragraph (a)(2) of Rule 485.
	If appropriate, check the following box:
o	this post-effective amendment designates a new effective date for a previously filed post-effective amendment.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness to its Registration Statement under Rule 485(b) under the Securities Act and had duly caused this Post-Effective Amendment to its Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of Jersey City, and State of New Jersey as of the 18^th day of December, 2012.

LORD ABBETT DEVELOPING GROWTH FUND, INC.
	BY:	/s/ Thomas R. Phillips
		Thomas R. Phillips
		Vice President and Assistant Secretary
	BY:	/s/ Joan A. Binstock
		Joan A. Binstock
		Chief Financial Officer and Vice President

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

Signatures		Title		Date
/s/ Robert S. Dow*	Chairman, Chief Executive		December 18, 2012
Robert S. Dow	Officer and Director
/s/ Daria L. Foster*	President and Director		December 18, 2012
Daria L. Foster
/s/ E. Thayer Bigelow*	Director		December 18, 2012
E. Thayer Bigelow
/s/ Evelyn E. Guernsey*	Director		December 18, 2012
Evelyn E. Guernsey
/s/ Robert B. Calhoun, Jr.*	Director		December 18, 2012
Robert B. Calhoun, Jr.
/s/ Julie A. Hill*	Director		December 18, 2012
Julie A. Hill
/s/ Franklin W. Hobbs*	Director		December 18, 2012
Franklin W. Hobbs
	Director		__________________
James M. McTaggart
/s/ Thomas J. Neff*	Director		December 18, 2012
Thomas J. Neff
/s/ James L .L. Tullis*	Director		December 18, 2012
James L. L. Tullis

* BY:	/s/ Thomas R. Phillips
	Thomas R. Phillips
	Attorney-in-Fact

POWER OF ATTORNEY

          Each person whose signature appears below on this Registration Statement hereby constitutes and appoints Lawrence H. Kaplan, Lawrence B. Stoller, John K. Forst, and Thomas R. Phillips, each of them, with full power to act without the other, his or her true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for him or her and in his or her name, place and stead, in any and all capacities (until revoked in writing) to sign any and all Registration Statements of each Fund enumerated on Exhibit A hereto for which such person serves as a Director/Trustee (including Registration Statements on Forms N-1A and N-14 and any amendments thereto), and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing ratifying and confirming all that said attorneys-in-fact and agents or any of them, or their or his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

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

Signatures		Title		Date
/s/ Robert S. Dow	Chairman, CEO		April 19, 2012
Robert S. Dow	and Director/Trustee
/s/ Daria L. Foster	President and		April 19, 2012
Daria L. Foster	Director/Trustee
/s/ E. Thayer Bigelow	Director/Trustee		April 19, 2012
E. Thayer Bigelow
/s/ Robert B. Calhoun, Jr.	Director/Trustee		April 19, 2012
Robert B. Calhoun, Jr.
/s/ Evelyn E. Guernsey	Director/Trustee		April 19, 2012
Evelyn E. Guernsey
/s/ Julie A. Hill	Director/Trustee		April 19, 2012
Julie A. Hill
/s/ Franklin W. Hobbs	Director/Trustee		April 19, 2012
Franklin W. Hobbs
/s/ Thomas J. Neff	Director/Trustee		April 19, 2012
Thomas J. Neff
/s/ James L .L. Tullis	Director/Trustee		April 19, 2012
James L. L. Tullis

EXHIBIT A

Lord Abbett Affiliated Fund, Inc.

Lord Abbett Bond-Debenture Fund, Inc.

Lord Abbett Developing Growth Fund, Inc.

Lord Abbett Equity Trust

Lord Abbett Global Fund, Inc.

Lord Abbett Investment Trust

Lord Abbett Mid Cap Stock Fund, Inc.

Lord Abbett Municipal Income Fund, Inc.

Lord Abbett Research Fund, Inc.

Lord Abbett Securities Trust

Lord Abbett Series Fund, Inc.

Lord Abbett Stock Appreciation Fund

Lord Abbett U.S. Government & Government Sponsored Enterprises Money Market Fund, Inc.

EXHIBIT INDEX

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