As filed with the Securities and Exchange Commission on June 2, 2005

                                                     Registration No. 333-88806

================================================================================
 
                                 UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

                           ------------------------

                       POST-EFFECTIVE AMENDMENT NO. 1 TO
                                   FORM S-8

                            REGISTRATION STATEMENT
                                     UNDER
                          THE SECURITIES ACT OF 1933

                           ------------------------

                        Selective Insurance Group, Inc.
            (Exact name of registrant as specified in its charter)

          New Jersey                                              22-2168890
(State or other jurisdiction of                               (I.R.S. Employer
 incorporation or organization)                              Identification No.)

                                --------------

                               40 Wantage Avenue
                             Branchville, NJ 07890
                   (Address of Principal Executive Offices)

                             Stock Option Plan III
                           (Full title of the plan)

                                --------------

                            Michael H. Lanza, Esq.
                   Senior Vice President and General Counsel
                        Selective Insurance Group, Inc.
                               40 Wantage Avenue
                             Branchville, NJ 07890
                    (Name and address of agent for service)

                                --------------

                                (973) 948-3000
         (Telephone number, including area code, of agent for service)

                                --------------
                                With a copy to:
                             Paul T. Schnell, Esq.
                   Skadden, Arps, Slate, Meagher & Flom LLP
                               Four Times Square
                            New York, NY 10036-6522
                                (212) 735-3000
                                --------------



                               EXPLANATORY NOTE

Selective Insurance Group, Inc. (the "Company") is filing this Post-Effective
Amendment No. 1 to Registration Statement on Form S-8 to deregister certain
securities previously registered by the Company pursuant to its Registration
Statement on Form S-8 filed with the Securities and Exchange Commission (the
"Commission") on May 22, 2002, File No. 333-88806 (the "2002 Form S-8"), with
respect to shares of the Company's common stock, par value $2.00 per share,
and the associated preferred share purchase rights (the "Common Stock"),
thereby registered for offer or sale pursuant to the Selective Insurance
Group, Inc. Stock Option Plan III ("Plan III"). A total of 1,448,128 shares of
Common Stock were initially registered for issuance, offer or sale under the
2002 Form S-8.

On April 27, 2005, the stockholders of the Company approved the Selective
Insurance Group, Inc. 2005 Omnibus Stock Plan (the "2005 Omnibus Plan"), which
replaces Plan III. No future awards will be made under Plan III. According to
the terms of the 2005 Omnibus Plan, the shares of Common Stock that were
available for grant under Plan III, but not actually subject to outstanding
awards or forfeited, cancelled, exchanged, surrendered, or not distributed, as
of April 27, 2005, are available for issuance under the 2005 Omnibus Plan. The
total number of such shares was 761,397 (the "Carryover Shares"). The
Carryover Shares are hereby deregistered. The 2002 Form S-8 otherwise
continues in effect as to the balance of the shares of Common Stock remaining
available for issuance, offer or sale pursuant thereto.

Contemporaneously with the filing of this Post-Effective Amendment No. 1 to
Registration Statement on Form S-8, the Company is filing a Registration
Statement on Form S-8 to register the shares of Common Stock now available for
issuance, offer or sale pursuant to the 2005 Omnibus Plan, including, but not
limited to, the Carryover Shares.

There may be shares of Common Stock registered in connection with Plan III
that are represented by awards under Plan III that, after April 27, 2005, are
forfeited, cancelled, exchanged, surrendered, not distributed, or otherwise
result in the return of shares to the Company. The Company may, from time to
time, file additional post-effective amendments to the 2002 Form S-8, and
additional Registration Statements on Form S-8, carrying forward such shares
for issuance, offer or sale in connection with the 2005 Omnibus Plan.



                                  SIGNATURES

                  Pursuant to the requirements of the Securities Act of 1933,
the registrant certifies that it has reasonable grounds to believe that it
meets all of the requirements for filing on Form S-8 and has duly caused this
Post-Effective Amendment No. 1 to Registration Statement on Form S-8 to be
signed on its behalf by the undersigned, thereunto duly authorized, in the
City of Branchville, State of New Jersey, on this 2nd day of June, 2005.

                                            SELECTIVE INSURANCE GROUP, INC.


                                            By:  /s/ Gregory E. Murphy
                                                --------------------------------
                                                Name:   Gregory E. Murphy
                                                Title:  Chairman, President and
                                                        Chief Executive Officer


                               POWER OF ATTORNEY

                  Each person whose signature appears below constitutes and
appoints Gregory E. Murphy, Michael H. Lanza and Michele N. Schumacher, and
each of them, with full power to act without the other, such person's true and
lawful attorneys-in-fact and agents, with full power of substitution and
resubstitution, for him and in his name, place and stead, in any and all
capacities, to sign this Post-Effective Amendment No. 1 to Registration
Statement on Form S-8, and any and all amendments thereto and to file the
same, with exhibits and schedules 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 necessary or desirable to be done in
and about the premises, as fully to all intents and purposes as he might or
could do in person, hereby ratifying and confirming all that said
attorneys-in-fact and agents, or any of them, or their or his 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 Post-Effective Amendment No. 1 to Registration Statement on Form S-8 has
been signed below by the following persons in the capacities and on the dates
indicated.







                                                                            
Signature                                  Title                                  Date
---------                                  -----                                  ----

/s/ Gregory E. Murphy                      Chairman, President and Chief          June 2, 2005
------------------------------------       Executive Officer (principal
Gregory E. Murphy                          executive officer)

/s/ Dale A. Thatcher                       Executive Vice President, Chief        June 2, 2005
------------------------------------       Financial Officer and Treasurer
Dale A. Thatcher                           (principal accounting and
                                           financial officer)

/s/ Paul D. Bauer                          Director                               June 2, 2005
------------------------------------
Paul D. Bauer


/s/ A. David Brown                         Director                               June 2, 2005
------------------------------------
A. David Brown


/s/ C. Edward Herder                       Director                               June 2, 2005
------------------------------------
C. Edward Herder


/s/ William M. Kearns, Jr.                 Director                               June 2, 2005
------------------------------------
William M. Kearns, Jr.


/s/ Joan M. Lamm-Tennant                   Director                               June 2, 2005
------------------------------------
Joan M. Lamm-Tennant


/s/ S. Griffin McClellan III               Director                               June 2, 2005
------------------------------------
S. Griffin McClellan III


/s/ Ronald L. O'Kelley                     Director                               June 2, 2005
------------------------------------
Ronald L. O'Kelley


/s/ John F. Rockart                        Director                               June 2, 2005
------------------------------------
John F. Rockart


/s/ William M. Rue                         Director                               June 2, 2005
------------------------------------
William M. Rue


/s/ J. Brian Thebault                      Director                               June 2, 2005
------------------------------------
J. Brian Thebault