<PAGE>   1
                                              Registration No. 333-
       -----------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8
                             Registration Statement
                                      under
                           The Securities Act of 1933


                     PHILADELPHIA CONSOLIDATED HOLDING CORP.
              ----------------------------------------------------
             (Exact name of registrant as specified in its charter)

             Pennsylvania                         23-2202671
        ----------------------        ----------------------------------
       (State of incorporation)      (I.R.S. Employer Identification No.)

           One Bala Plaza, Suite 100, Bala Cynwyd, Pennsylvania 19004
           ----------------------------------------------------------
               (Address of principal executive offices) (Zip Code)

                        Philadelphia Insurance Companies
                          Employee Stock Purchase Plan
                        --------------------------------
                            (Full title of the plan)

                              Mr. James J. Maguire,
                             Chief Executive Officer
                                       or
                           Craig P. Keller, Secretary
                     Philadelphia Consolidated Holding Corp.
                            One Bala Plaza, Suite 100
                         Bala Cynwyd, Pennsylvania 19004
                     (Name and address of agent for service)

                                 (610) 617-7900
           -----------------------------------------------------------
          (Telephone number, including area code, of agent for service)

                                   Copies to:
                           Michael M. Sherman, Esquire
                     Wolf, Block, Schorr and Solis-Cohen LLP
                          1650 Arch Street - 22nd Floor
                           Philadelphia, PA 19103-2097
                                 (215) 977-2236
                               FAX: (215) 977-2334
<PAGE>   2
                         CALCULATION OF REGISTRATION FEE

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

<TABLE>
<CAPTION>
                                              Proposed             Proposed
   Title of                                   Maximum               Maximum              Amount of
Securities to be     Amount to be          Offering Price          Aggregate            Registration
  Registered         Registered(1)          Per Share(2)         Offering Price             Fee
  ----------         -------------          ------------         --------------         ------------
<S>                  <C>                     <C>                 <C>                     <C>
Common Stock,        500,000                 $17.375             $8,687,500              $2,293.50
No par value
</TABLE>

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

(1)      Pursuant to Rule 416 under the Securities Act of 1933, as amended, this
         registration statement also covers such additional shares as may
         hereafter be offered or issued to prevent dilution resulting from stock
         splits, stock dividends, recapitalizations or certain other capital
         adjustments.

(2)      Pursuant to Rules 457(c) and 457(h)(1) under the Securities Act of
         1933, as amended, represents the average of the high and low prices for
         the Common Stock as listed in the Nasdaq National Market of the Nasdaq
         Stock Market, Inc. on June 20, 2000.

--------------------------------------------------------------------------------
<PAGE>   3
                           INCORPORATION BY REFERENCE

                  Pursuant to General Instruction E of Form S-8 under the
Securities Act of 1933, as amended, the contents of the registrant's
registration statement on Form S-8, filed with the SEC on September 5, 1995
(Commission File No. 33-81346) are incorporated herein by reference.

                                      II-1
<PAGE>   4
                        SIGNATURES AND POWER OF ATTORNEY

                  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
registration statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in Bala Cynwyd, Pennsylvania, on this 20th day of June, 2000.

                                   PHILADELPHIA CONSOLIDATED HOLDING CORP.


                                   By:     /s/ James J. Maguire
                                           James J. Maguire
                                           Chairman of the Board of Directors
                                           and Chief Executive Officer


                                      II-2
<PAGE>   5
                  KNOW ALL MEN BY THESE PRESENTS, that each person whose
signature appears below constitutes and appoints James J. Maguire and Craig P.
Keller, and each of them, the undersigned's true and lawful attorney-in-fact and
agent, with full power of substitution and resubstitution, for the undersigned
and in the undersigned's name, place and stead, in any and all capacities, to
sign any and all amendments to this registration statement (including, without
limitation, post-effective amendments to this registration statement), and to
file the same, with all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, granting unto said
attorney-in-fact and agent full power and authority to do and perform each and
every act and thing requisite and necessary to be done in and about the
premises, as fully to all intents and purposes as the undersigned might or could
do in person, hereby ratifying and confirming all that said attorney-in-fact and
agent, 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 registration statement has been signed by the following persons in the
capacities indicated, on the date indicated.

<TABLE>
<CAPTION>
         Signature                                      Title                                     Date
         ---------                                      -----                                     ----
<S>                                         <C>                                               <C>

/s/ James J. Maguire                        Chairman of the Board of Directors,               June 20, 2000
----------------------------------
James J. Maguire                            Chief Executive Officer and Director
                                            (Principal Executive Officer)

/s/ Craig P. Keller                         Senior Vice President, Secretary,                 June 20, 2000
----------------------------------
Craig P. Keller                             Treasurer and Chief Financial
                                            Officer (Principal Financial and
                                            Accounting Officer)

/s/ James J. Maguire, Jr.                   President, Chief Operating Officer                June 20, 2000
----------------------------------
James J. Maguire, Jr.                       and Director

/s/ Sean S. Sweeney                         Executive Vice President and                      June 20, 2000
----------------------------------
Sean S. Sweeney                             Director

/s/ William J. Henrich, Jr.                 Director                                          June 20, 2000
----------------------------------
William J. Henrich, Jr.

/s/ Roger R. Larson                         Director                                          June 20, 2000
----------------------------------
Roger R. Larson

/s/ Paul R. Hertel, Jr.                     Director                                          June 20, 2000
----------------------------------
Paul R. Hertel, Jr.

/s/ Thomas J. McHugh                        Director                                          June 20, 2000
----------------------------------
</TABLE>

                                      II-3
<PAGE>   6
<TABLE>
<S>                                         <C>                                               <C>
Thomas J. McHugh

/s/ Michael J. Morris                       Director                                          June 20, 2000
----------------------------------
Michael J. Morris

/s/ Dirk Stuurop                            Director                                          June 20, 2000
----------------------------------
Dirk Stuurop

/s/ J. Eustace Wolfington                   Director                                          June 20, 2000
----------------------------------
J. Eustace Wolfington
</TABLE>

                                      II-4
<PAGE>   7
                        PHILADELPHIA INSURANCE COMPANIES
                          EMPLOYEE STOCK PURCHASE PLAN


                       REGISTRATION STATEMENT ON FORM S-8


                                  EXHIBIT INDEX

<TABLE>
<CAPTION>
EXHIBIT NO.          DOCUMENT                                                                 METHOD OF FILING
-----------          --------                                                                 ----------------

<S>                  <C>                                                                      <C>
4.1                  Philadelphia Insurance Companies Employee
                     Stock Purchase Plan.                                                             *

4.2                  Amendment to Philadelphia Insurance Companies
                     Employee Stock Purchase Plan dated July 21, 1998.                                *

4.3                  Amendment to Philadelphia Insurance Companies
                     Employee Stock Purchase Plan dated April 5, 2000.                                *

 5                   Opinion of Wolf, Block, Schorr and Solis-Cohen LLP.                              *

23.1                 Consent of PricewaterhouseCoopers L.L.P.,
                     independent accountants.                                                         *

23.2                 Consent of Wolf, Block, Schorr and Solis-Cohen LLP
                     (contained in Exhibit 5).                                                        *

24                   Power of Attorney (included on signature page in
                     Part II of the registration statement).                                          *
</TABLE>


* Filed electronically herewith.
[{"type": "S-8", "sequence": "1", "filename": "0001.txt", "description": "REGISTRATION STATEMENT", "secsgml_size_bytes": 10999}]
{"company-data": {"conformed-name": "PHILADELPHIA CONSOLIDATED HOLDING CORP", "cik": "0000909109", "assigned-sic": "6331", "irs-number": "232202671", "state-of-incorporation": "PA", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-39794", "film-number": "658550"}, "business-address": {"street1": "ONE BALA PLAZA", "street2": "SUITE 100", "city": "WYNNEWOOD", "state": "PA", "zip": "19004", "phone": "6106428400"}, "mail-address": {"street1": "ONE BALA PLAZA", "street2": "SUITE 100", "city": "BALA CYNWYD", "state": "PA", "zip": "19004"}, "former-company": {"former-conformed-name": "MAGUIRE HOLDING CORP", "date-changed": "19930714"}}
1
                                              Registration No. 333-
       -----------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8
                             Registration Statement
                                      under
                           The Securities Act of 1933

                     PHILADELPHIA CONSOLIDATED HOLDING CORP.
              ----------------------------------------------------
             (Exact name of registrant as specified in its charter)

             Pennsylvania                         23-2202671
        ----------------------        ----------------------------------
       (State of incorporation)      (I.R.S. Employer Identification No.)

           One Bala Plaza, Suite 100, Bala Cynwyd, Pennsylvania 19004
           ----------------------------------------------------------
               (Address of principal executive offices) (Zip Code)

                        Philadelphia Insurance Companies
                          Employee Stock Purchase Plan
                        --------------------------------
                            (Full title of the plan)

                              Mr. James J. Maguire,
                             Chief Executive Officer
                                       or
                           Craig P. Keller, Secretary
                     Philadelphia Consolidated Holding Corp.
                            One Bala Plaza, Suite 100
                         Bala Cynwyd, Pennsylvania 19004
                     (Name and address of agent for service)

                                 (610) 617-7900
           -----------------------------------------------------------
          (Telephone number, including area code, of agent for service)

                                   Copies to:
                           Michael M. Sherman, Esquire
                     Wolf, Block, Schorr and Solis-Cohen LLP
                          1650 Arch Street - 22nd Floor
                           Philadelphia, PA 19103-2097
                                 (215) 977-2236
                               FAX: (215) 977-2334
2
                         CALCULATION OF REGISTRATION FEE

--------------------------------------------------------------------------------
Proposed             Proposed
   Title of                                   Maximum               Maximum              Amount of
Securities to be     Amount to be          Offering Price          Aggregate            Registration
  Registered         Registered(1)          Per Share(2)         Offering Price             Fee
  ----------         -------------          ------------         --------------         ------------
Common Stock,        500,000                 $17.375             $8,687,500              $2,293.50
No par value
--------------------------------------------------------------------------------

(1)      Pursuant to Rule 416 under the Securities Act of 1933, as amended, this
         registration statement also covers such additional shares as may
         hereafter be offered or issued to prevent dilution resulting from stock
         splits, stock dividends, recapitalizations or certain other capital
         adjustments.

(2)      Pursuant to Rules 457(c) and 457(h)(1) under the Securities Act of
         1933, as amended, represents the average of the high and low prices for
         the Common Stock as listed in the Nasdaq National Market of the Nasdaq
         Stock Market, Inc. on June 20, 2000.

--------------------------------------------------------------------------------
3
                           INCORPORATION BY REFERENCE

                  Pursuant to General Instruction E of Form S-8 under the
Securities Act of 1933, as amended, the contents of the registrant's
registration statement on Form S-8, filed with the SEC on September 5, 1995
(Commission File No. 33-81346) are incorporated herein by reference.

                                      II-1
4
                        SIGNATURES AND POWER OF ATTORNEY

                  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
registration statement to be signed on its behalf by the undersigned, thereunto
duly authorized, in Bala Cynwyd, Pennsylvania, on this 20th day of June, 2000.

                                   PHILADELPHIA CONSOLIDATED HOLDING CORP.

                                   By:     /s/ James J. Maguire
                                           James J. Maguire
                                           Chairman of the Board of Directors
                                           and Chief Executive Officer

                                      II-2
5
                  KNOW ALL MEN BY THESE PRESENTS, that each person whose
signature appears below constitutes and appoints James J. Maguire and Craig P.
Keller, and each of them, the undersigned's true and lawful attorney-in-fact and
agent, with full power of substitution and resubstitution, for the undersigned
and in the undersigned's name, place and stead, in any and all capacities, to
sign any and all amendments to this registration statement (including, without
limitation, post-effective amendments to this registration statement), and to
file the same, with all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, granting unto said
attorney-in-fact and agent full power and authority to do and perform each and
every act and thing requisite and necessary to be done in and about the
premises, as fully to all intents and purposes as the undersigned might or could
do in person, hereby ratifying and confirming all that said attorney-in-fact and
agent, 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 registration statement has been signed by the following persons in the
capacities indicated, on the date indicated.
Signature                                      Title                                     Date
         ---------                                      -----                                     ----
/s/ James J. Maguire                        Chairman of the Board of Directors,               June 20, 2000
----------------------------------
James J. Maguire                            Chief Executive Officer and Director
                                            (Principal Executive Officer)

/s/ Craig P. Keller                         Senior Vice President, Secretary,                 June 20, 2000
----------------------------------
Craig P. Keller                             Treasurer and Chief Financial
                                            Officer (Principal Financial and
                                            Accounting Officer)

/s/ James J. Maguire, Jr.                   President, Chief Operating Officer                June 20, 2000
----------------------------------
James J. Maguire, Jr.                       and Director

/s/ Sean S. Sweeney                         Executive Vice President and                      June 20, 2000
----------------------------------
Sean S. Sweeney                             Director

/s/ William J. Henrich, Jr.                 Director                                          June 20, 2000
----------------------------------
William J. Henrich, Jr.

/s/ Roger R. Larson                         Director                                          June 20, 2000
----------------------------------
Roger R. Larson

/s/ Paul R. Hertel, Jr.                     Director                                          June 20, 2000
----------------------------------
Paul R. Hertel, Jr.

/s/ Thomas J. McHugh                        Director                                          June 20, 2000
----------------------------------
II-3
6
Thomas J. McHugh

/s/ Michael J. Morris                       Director                                          June 20, 2000
----------------------------------
Michael J. Morris

/s/ Dirk Stuurop                            Director                                          June 20, 2000
----------------------------------
Dirk Stuurop

/s/ J. Eustace Wolfington                   Director                                          June 20, 2000
----------------------------------
J. Eustace Wolfington
II-4
7
                        PHILADELPHIA INSURANCE COMPANIES
                          EMPLOYEE STOCK PURCHASE PLAN

                       REGISTRATION STATEMENT ON FORM S-8

                                  EXHIBIT INDEX
EXHIBIT NO.          DOCUMENT                                                                 METHOD OF FILING
-----------          --------                                                                 ----------------
4.1                  Philadelphia Insurance Companies Employee
                     Stock Purchase Plan.                                                             *

4.2                  Amendment to Philadelphia Insurance Companies
                     Employee Stock Purchase Plan dated July 21, 1998.                                *

4.3                  Amendment to Philadelphia Insurance Companies
                     Employee Stock Purchase Plan dated April 5, 2000.                                *

 5                   Opinion of Wolf, Block, Schorr and Solis-Cohen LLP.                              *

23.1                 Consent of PricewaterhouseCoopers L.L.P.,
                     independent accountants.                                                         *

23.2                 Consent of Wolf, Block, Schorr and Solis-Cohen LLP
                     (contained in Exhibit 5).                                                        *

24                   Power of Attorney (included on signature page in
                     Part II of the registration statement).                                          *
* Filed electronically herewith.