content: <PAGE>   1
  
  
       AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JULY 26, 2000
                                                        REGISTRATION NO. 333-_____
  
                         SECURITIES AND EXCHANGE COMMISSION
                               WASHINGTON, D.C. 20549
  
                                      FORM S-8
                               REGISTRATION STATEMENT
                                        UNDER
                         THE SECURITIES EXCHANGE ACT OF 1933
  
                           ARCH COMMUNICATIONS GROUP, INC.
   -------------------------------------------------------------------------------
               (Exact Name of Registrant as Specified in Its Charter)
  
                       DELAWARE                                  31-1358569
   -------------------------------------------------------------------------------
   (State or Other Jurisdiction of Incorporation)              (I.R.S. Employer
                                                              Identification No.)
  
               1800 WEST PARK DRIVE, SUITE 250, WESTBOROUGH, MA 01581
   -------------------------------------------------------------------------------
                 (Address of Principal Executive Offices) (Zip Code)
  
                      NON-EMPLOYEE DIRECTORS' STOCK OPTION PLAN
   -------------------------------------------------------------------------------
                              (Full title of the plan)
  
                                C. Edward Baker, Jr.
                        Chairman and Chief Executive Officer
                           Arch Communications Group, Inc.
                           1800 West Park Drive, Suite 250
                                Westborough, MA 01581
   -------------------------------------------------------------------------------
                       (Name and address of agent for service)
  
                                   (508) 870-6700
   -------------------------------------------------------------------------------
            (Telephone number, including area code, of agent for service)
                           CALCULATION OF REGISTRATION FEE
  
  <TABLE>
  <CAPTION>
  
                                                                      Proposed
           Title of                                   Proposed         Maximum
          Securities                 Amount to        Maximum         Aggregate     Amount of
             to be                       be        Offering Price     Offering     Registration
          Registered                Registered       Per Share          Price         Fee
          -----------               ----------     --------------     ---------    ------------
  <S>                                 <C>              <C>            <C>             <C>
  Common Stock, $.01 par value        150,000          $5.64(1)       $846,000(1)     $224
                                      Shares
  </TABLE>
  
  -----------------
  
           (1) Computed in accordance with Rules 457(c) and (h) under the
  Securities Act of 1933, as amended, based upon the average of the high and low
  prices of the Common Stock as reported by Nasdaq National Market on July 24,
  2000.
  
                                 Page 1 of 6 pages.
                           Exhibit Index begins on page 5.
  
  
  <PAGE>   2
  
  
                       STATEMENT OF INCORPORATION BY REFERENCE
  
  
  
           Except as otherwise set forth below, this Registration Statement on
  Form S-8 incorporates by reference the contents of the Registration Statement on
  Form S-8, File Nos. 33-87940 and 333-79993, relating to the Non-Employee
  Directors' Stock Option Plan.
  
                                        -2-
  
  <PAGE>   3
  
  
                                     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 Registration
  Statement to be signed on its behalf by the undersigned, thereunto duly
  authorized, in the Town of Westborough, on this 24th day of July, 2000.
  
  
  
                                          ARCH COMMUNICATIONS GROUP, INC.
  
  
  
  
                                          By: /s/ C. Edward Baker, Jr.
                                             -----------------------------------
                                                 C. Edward Baker, Jr.
                                                 Chairman of the Board and Chief
                                                 Executive Officer
  
  
                                  POWER OF ATTORNEY
  
           We, the undersigned officers and directors of Arch Communications
  Group, Inc. hereby severally constitute and appoint C. Edward Baker, Jr., Gerald
  J. Cimmino, Patricia A. Gray and David A. Westenberg, and each of them singly,
  our true and lawful attorneys with full power to them, and each of them singly,
  to sign for us and in our names, in the capacities indicated below, the
  Registration Statement on Form S-8 filed herewith and any and all amendments to
  said Registration Statement and generally to do all such things in our name and
  behalf in our capacities as officers and directors to enable Arch Communications
  Group, Inc. to comply with the provisions of the Securities Act, and all
  requirements of the Securities and Exchange Commission, hereby ratifying and
  confirming our signatures as they may be signed by our said attorneys, or any of
  them, to said Registration Statement and any and all amendments thereto.
  
  
                                        -3-
  <PAGE>   4
  
  
  
           Pursuant to the requirements of the Securities Act of 1933, this
  Registration Statement has been signed by the following persons in the
  capacities and on the date indicated.
  
  <TABLE>
  <CAPTION>
  
                  SIGNATURE                               TITLE                           DATE
                  ---------                               -----                           ----
  <S>                                    <C>                                          <C>
  
  /s/ C. Edward Baker, Jr.               Chairman of the Board of Directors and       July 24, 2000
  --------------------------------       Chief Executive Officer
  C. Edward Baker, Jr.                   (Principal Executive Officer)
  
  /s/ J. Roy Pottle                      Executive Vice President and Chief           July 24, 2000
  --------------------------------       Financial Officer
  J. Roy Pottle                          (Principal Financial Officer and
                                         Principal Accounting Officer)
  
  /s/ Edwin M. Banks                     Director                                     July 24, 2000
  --------------------------------
  Edwin M. Banks
  
  /s/ R. Schorr Berman
  --------------------------------       Director                                     July 24, 2000
  R. Schorr Berman
  
  /s/ James S. Hughes                    Director                                     July 24, 2000
  --------------------------------
  James S. Hughes
  
  /s/ John Kornreich                     Director                                     July 24, 2000
  --------------------------------
  John Kornreich
  
  /s/ H. Sean Mathis
  ---------------------------------      Director                                     July 24, 2000
  H. Sean Mathis
  
  /s/ Allan L. Rayfield                  Director                                     July 24, 2000
  ---------------------------------
  Allan L. Rayfield
  
  /s/ John B. Saynor                     Director                                     July 24, 2000
  ---------------------------------
  John B. Saynor
  
  /s/ John A. Shane                      Director                                     July 24, 2000
  ---------------------------------
  John A. Shane
  </TABLE>
  
  
                                        -4-
  
  <PAGE>   5
  
                                    EXHIBIT INDEX
  
  <TABLE>
  <CAPTION>
  
  Exhibit
  Number                         Description
  -------                        -----------
  <S>          <C>
    4.1(1)     Restated Certificate of Incorporation
  
  
    4.2(2)     Certificate of Designations establishing the Series B Junior
               Participating Preferred Stock filed with the Secretary of State of the State of
               Delaware on October 19, 1995
  
    4.3(1)     Certificate of Correction filed with the Secretary of State of the State of Delaware on
               February 15, 1996
  
    4.4(3)     Certificate of Amendment of Restated Certificate of Incorporation filed with the
               Secretary of State of the State of Delaware on June 4, 1996
  
    4.5(4)     Certificate of Designations establishing the Series C
               Convertible Preferred Stock filed with the Secretary of State
               of the State of Delaware on June 29, 1998
  
    4.6(5)     Certificate of Amendment of Restated Certificate of Incorporation filed with the
               Secretary of State of the State of Delaware on May 27, 1999
  
    4.7(5)     Certificate of Amendment of Restated Certificate of Incorporation filed with the
               Secretary of State of the State of Delaware on June 16, 1999
  
    4.8(6)     Certificate of Amendment filed with the Secretary of State of the State of Delaware on
               April 3, 2000
  
    4.9(6)     Certificate of Designations establishing the Series D and E
               Preferred Stock filed with the Secretary of State of the State
               of Delaware on April 28, 2000
  
    4.10(1)    Amended By-Laws of the Registrant
  
    5.1        Opinion of Hale and Dorr LLP
  
   23.1        Consent of Hale and Dorr LLP (included in Exhibit 5.1)
  
   23.2        Consent of Arthur Andersen LLP
  
   24.1        Power of Attorney (included in the signature pages of this Registration Statement)
  </TABLE>
  
  ---------------
  
  (1)      Incorporated by reference from the Registrant's Registration Statement
           on Form S-3 (File No. 333-542).
  
  (2)      Incorporated by reference from the Registrant's Current Report on
           Form 8-K dated October 13, 1995 and filed on October 24, 1995.
  
                                        -5-
  <PAGE>   6
  
  
  (3)      Incorporated by reference from the Registrant's Registration Statement
           on Form S-8 (File no. 333-07333).
  
  (4)      Incorporated by reference from the Registrant's Current Report on
           Form 8-K dated June 26, 1998 and filed on July 23, 1998.
  
  (5)      Incorporated by reference from the Registrant's Registration
           Statement on Form S-8 (File no. 333-42240).
  
  (6)      Incorporated by reference from the Registrant's Registration Statement
           on Form S-4 (File no. 333-95677).
  
  
  
                                        -6-
metadata_documents: [{"type": "S-8", "sequence": "1", "filename": "s-8.txt", "description": "ARCH COMMUNICATIONS GROUP, INC.", "secsgml_size_bytes": 10571}]
metadata_filer: {"company-data": {"conformed-name": "ARCH COMMUNICATIONS GROUP INC /DE/", "cik": "0000915390", "assigned-sic": "4812", "irs-number": "311358569", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-42248", "film-number": "679020"}, "business-address": {"street1": "1800 W PARK DR", "street2": "STE 250", "city": "WESTBOROUGH", "state": "MA", "zip": "01581", "phone": "5088706700"}, "mail-address": {"street1": "1800 W PARK DR", "street2": "STE 250", "city": "WESTBOROUGH", "state": "MA", "zip": "01581"}, "former-company": {"former-conformed-name": "USA MOBILE COMMUNICATIONS HOLDINGS INC /DE/", "date-changed": "19950519"}}
text: 1
  
       AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JULY 26, 2000
                                                        REGISTRATION NO. 333-_____
  
                         SECURITIES AND EXCHANGE COMMISSION
                               WASHINGTON, D.C. 20549
  
                                      FORM S-8
                               REGISTRATION STATEMENT
                                        UNDER
                         THE SECURITIES EXCHANGE ACT OF 1933
  
                           ARCH COMMUNICATIONS GROUP, INC.
   -------------------------------------------------------------------------------
               (Exact Name of Registrant as Specified in Its Charter)
  
                       DELAWARE                                  31-1358569
   -------------------------------------------------------------------------------
   (State or Other Jurisdiction of Incorporation)              (I.R.S. Employer
                                                              Identification No.)
  
               1800 WEST PARK DRIVE, SUITE 250, WESTBOROUGH, MA 01581
   -------------------------------------------------------------------------------
                 (Address of Principal Executive Offices) (Zip Code)
  
                      NON-EMPLOYEE DIRECTORS' STOCK OPTION PLAN
   -------------------------------------------------------------------------------
                              (Full title of the plan)
  
                                C. Edward Baker, Jr.
                        Chairman and Chief Executive Officer
                           Arch Communications Group, Inc.
                           1800 West Park Drive, Suite 250
                                Westborough, MA 01581
   -------------------------------------------------------------------------------
                       (Name and address of agent for service)
  
                                   (508) 870-6700
   -------------------------------------------------------------------------------
            (Telephone number, including area code, of agent for service)
                           CALCULATION OF REGISTRATION FEE
  Proposed
           Title of                                   Proposed         Maximum
          Securities                 Amount to        Maximum         Aggregate     Amount of
             to be                       be        Offering Price     Offering     Registration
          Registered                Registered       Per Share          Price         Fee
          -----------               ----------     --------------     ---------    ------------
  Common Stock, $.01 par value        150,000          $5.64(1)       $846,000(1)     $224
                                      Shares
  -----------------
  
           (1) Computed in accordance with Rules 457(c) and (h) under the
  Securities Act of 1933, as amended, based upon the average of the high and low
  prices of the Common Stock as reported by Nasdaq National Market on July 24,
  2000.
  
                                 Page 1 of 6 pages.
                           Exhibit Index begins on page 5.
  2
  
                       STATEMENT OF INCORPORATION BY REFERENCE
  
           Except as otherwise set forth below, this Registration Statement on
  Form S-8 incorporates by reference the contents of the Registration Statement on
  Form S-8, File Nos. 33-87940 and 333-79993, relating to the Non-Employee
  Directors' Stock Option Plan.
  
                                        -2-
  3
  
                                     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 Registration
  Statement to be signed on its behalf by the undersigned, thereunto duly
  authorized, in the Town of Westborough, on this 24th day of July, 2000.
  
                                          ARCH COMMUNICATIONS GROUP, INC.
  
                                          By: /s/ C. Edward Baker, Jr.
                                             -----------------------------------
                                                 C. Edward Baker, Jr.
                                                 Chairman of the Board and Chief
                                                 Executive Officer
  
                                  POWER OF ATTORNEY
  
           We, the undersigned officers and directors of Arch Communications
  Group, Inc. hereby severally constitute and appoint C. Edward Baker, Jr., Gerald
  J. Cimmino, Patricia A. Gray and David A. Westenberg, and each of them singly,
  our true and lawful attorneys with full power to them, and each of them singly,
  to sign for us and in our names, in the capacities indicated below, the
  Registration Statement on Form S-8 filed herewith and any and all amendments to
  said Registration Statement and generally to do all such things in our name and
  behalf in our capacities as officers and directors to enable Arch Communications
  Group, Inc. to comply with the provisions of the Securities Act, and all
  requirements of the Securities and Exchange Commission, hereby ratifying and
  confirming our signatures as they may be signed by our said attorneys, or any of
  them, to said Registration Statement and any and all amendments thereto.
  
                                        -3-
  4
  
           Pursuant to the requirements of the Securities Act of 1933, this
  Registration Statement has been signed by the following persons in the
  capacities and on the date indicated.
  SIGNATURE                               TITLE                           DATE
                  ---------                               -----                           ----
  /s/ C. Edward Baker, Jr.               Chairman of the Board of Directors and       July 24, 2000
  --------------------------------       Chief Executive Officer
  C. Edward Baker, Jr.                   (Principal Executive Officer)
  
  /s/ J. Roy Pottle                      Executive Vice President and Chief           July 24, 2000
  --------------------------------       Financial Officer
  J. Roy Pottle                          (Principal Financial Officer and
                                         Principal Accounting Officer)
  
  /s/ Edwin M. Banks                     Director                                     July 24, 2000
  --------------------------------
  Edwin M. Banks
  
  /s/ R. Schorr Berman
  --------------------------------       Director                                     July 24, 2000
  R. Schorr Berman
  
  /s/ James S. Hughes                    Director                                     July 24, 2000
  --------------------------------
  James S. Hughes
  
  /s/ John Kornreich                     Director                                     July 24, 2000
  --------------------------------
  John Kornreich
  
  /s/ H. Sean Mathis
  ---------------------------------      Director                                     July 24, 2000
  H. Sean Mathis
  
  /s/ Allan L. Rayfield                  Director                                     July 24, 2000
  ---------------------------------
  Allan L. Rayfield
  
  /s/ John B. Saynor                     Director                                     July 24, 2000
  ---------------------------------
  John B. Saynor
  
  /s/ John A. Shane                      Director                                     July 24, 2000
  ---------------------------------
  John A. Shane
  -4-
  5
  
                                    EXHIBIT INDEX
  Exhibit
  Number                         Description
  -------                        -----------
  4.1(1)     Restated Certificate of Incorporation
  
    4.2(2)     Certificate of Designations establishing the Series B Junior
               Participating Preferred Stock filed with the Secretary of State of the State of
               Delaware on October 19, 1995
  
    4.3(1)     Certificate of Correction filed with the Secretary of State of the State of Delaware on
               February 15, 1996
  
    4.4(3)     Certificate of Amendment of Restated Certificate of Incorporation filed with the
               Secretary of State of the State of Delaware on June 4, 1996
  
    4.5(4)     Certificate of Designations establishing the Series C
               Convertible Preferred Stock filed with the Secretary of State
               of the State of Delaware on June 29, 1998
  
    4.6(5)     Certificate of Amendment of Restated Certificate of Incorporation filed with the
               Secretary of State of the State of Delaware on May 27, 1999
  
    4.7(5)     Certificate of Amendment of Restated Certificate of Incorporation filed with the
               Secretary of State of the State of Delaware on June 16, 1999
  
    4.8(6)     Certificate of Amendment filed with the Secretary of State of the State of Delaware on
               April 3, 2000
  
    4.9(6)     Certificate of Designations establishing the Series D and E
               Preferred Stock filed with the Secretary of State of the State
               of Delaware on April 28, 2000
  
    4.10(1)    Amended By-Laws of the Registrant
  
    5.1        Opinion of Hale and Dorr LLP
  
   23.1        Consent of Hale and Dorr LLP (included in Exhibit 5.1)
  
   23.2        Consent of Arthur Andersen LLP
  
   24.1        Power of Attorney (included in the signature pages of this Registration Statement)
  ---------------
  
  (1)      Incorporated by reference from the Registrant's Registration Statement
           on Form S-3 (File No. 333-542).
  
  (2)      Incorporated by reference from the Registrant's Current Report on
           Form 8-K dated October 13, 1995 and filed on October 24, 1995.
  
                                        -5-
  6
  
  (3)      Incorporated by reference from the Registrant's Registration Statement
           on Form S-8 (File no. 333-07333).
  
  (4)      Incorporated by reference from the Registrant's Current Report on
           Form 8-K dated June 26, 1998 and filed on July 23, 1998.
  
  (5)      Incorporated by reference from the Registrant's Registration
           Statement on Form S-8 (File no. 333-42240).
  
  (6)      Incorporated by reference from the Registrant's Registration Statement
           on Form S-4 (File no. 333-95677).
  
                                        -6-