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EX-4.1


                       AMENDMENT NO. 6 TO RIGHTS AGREEMENT


                                                                     EXHIBIT 4.1

This Amendment No. 6 dated as of April 12, 2000 hereby amends the Rights
Agreement originally dated as of October 13, 1995, as amended on June 29, 1998,
August 18, 1998, September 3, 1998, May 14, 1999 and November 15, 1999 (the
"Agreement"), between Arch Communications Group, Inc., a Delaware corporation
(the "Company"), and The Bank of New York, a national banking association, as
Rights Agent (the "Rights Agent").


                              W I T N E S S E T H:

WHEREAS, no Person has become an Acquiring Person as such terms are defined in
the Agreement; and

WHEREAS, the Company has directed the Rights Agent to enter into this Amendment
No. 6 pursuant to Section 27 of the Agreement;

NOW, THEREFORE, in consideration of the premises and mutual agreements set forth
herein, the parties hereby agree as follows:

1.     Section 1(ii) of the Agreement is hereby deleted in its entirety and
the following substituted in lieu thereof:

         (ii) "Exempted Person" shall mean, prior to the PageNet Effective Time
         (as defined below): (A) W. R. Huff Asset Management Co., L.L.C.,
         together with its Affiliates (collectively, "Huff"), unless and until
         such time as Huff, directly or indirectly, becomes the Beneficial Owner
         of Common Stock in excess of the Huff Exempt Threshold (as defined
         below), in which event Huff immediately shall cease to be an Exempted
         Person; (B) Whippoorwill Associates, Inc., together with its
         Affiliates, including, without limitation, any accounts and investment
         funds managed by it or its Affiliates (collectively, "Whippoorwill"),
         unless and until such time as Whippoorwill, directly or indirectly,
         becomes the Beneficial Owner of Common Stock in excess of the
         Whippoorwill Exempt Threshold (as defined below), in which case
         Whippoorwill immediately shall cease to be an Exempted Person; (C)
         Resurgence Asset Management, L.L.C., together with its Affiliates
         (collectively, "Resurgence"), unless and until such time as Resurgence,
         directly or indirectly, becomes the Beneficial Owner of Common Stock in
         excess of the Resurgence Exempt Threshold (as defined below), in which
         event Resurgence immediately shall cease to be an Exempted Person; and
         (D) Citigroup Inc., together with its Affiliates, including, without
         limitation, any accounts and investment


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         funds managed by it or its Affiliates (collectively, "Citigroup"),
         unless and until such time as Citigroup, directly or indirectly,
         becomes the Beneficial Owner of Common Stock in excess of the Citigroup
         Exempt Threshold (as defined below), in which case Citigroup
         immediately shall cease to be an Exempted Person. "Exempted Person"
         shall mean, on or after the PageNet Effective Time, any Person that
         acquires shares of Common Stock ("Merger Shares") in exchange for
         shares of common stock of Paging Network, Inc. ("PageNet") upon the
         consummation of the merger between PageNet and St. Louis Acquisition
         Corp., a wholly owned subsidiary of the Company ("MergerSub"), pursuant
         to that Agreement and Plan of Merger among PageNet, the Company and
         MergerSub dated as of November 7, 1999 as the same may be amended (the
         "PageNet Merger Agreement") unless and until such time as such Person,
         directly or indirectly becomes the Beneficial Owner of Common Stock in
         excess of the Merger Exempt Threshold (as defined below). For purposes
         of this Agreement: (A) the Huff Exempt Threshold shall mean 23.9% of
         the Common Stock then outstanding; (B) the Whippoorwill Exempt
         Threshold shall mean 21.3% of the Common Stock then outstanding; (C)
         the Resurgence Exempt Threshold shall mean (I) prior to the Resurgence
         Exchange (as defined below) 19.0% of the Common Stock then outstanding
         and (II) after the Resurgence Exchange 25.0% of the Common Stock then
         outstanding, provided that after the Resurgence Exchange such
         Resurgence Exempt Threshold shall be reduced 1% for each 1% reduction
         in the Beneficial Ownership of Common Stock by Resurgence resulting
         from sales, transfers or other dispositions of the Company's capital
         stock effected after the Resurgence Exchange as reflected in any filing
         by Resurgence on Schedule 13D or 13G or any successor form made with
         the Securities and Exchange Commission; (D) the Citigroup Exempt
         Threshold shall mean 18.0% of the Common Stock then outstanding; and
         (E) the Merger Exempt Threshold shall mean 20.0% of the Common Stock
         then outstanding (provided that a majority of the shares of Common
         Stock Beneficially Owned by such Person are Merger Shares). For
         purposes of this Agreement, the Huff Exempt Threshold, the Whippoorwill
         Exempt Threshold, the Resurgence Exempt Threshold, the Citigroup Exempt
         Threshold and the Merger Exempt Threshold are collectively referred to
         herein as the "Exempt Threshold." For purposes of this Section 1(ii):
         (A) none of Huff, Credit Suisse First Boston Corporation (or its
         Affiliates), Whippoorwill or The Northwestern Mutual Life Insurance
         Company (or its Affiliates) shall be deemed the Beneficial Owner of any
         shares of Common Stock that are Beneficially Owned by any other Person
         solely as a result of any such Person's execution and performance of
         any Standby Purchase Commitment (as such term is defined in the Plan
         and Agreement of Merger between the Company, Farm Team


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         Corp., a wholly-owned Subsidiary of the Company, MobileMedia
         Corporation and MobileMedia Communications, Inc., dated as of August
         18, 1998) (as amended, the "Merger Agreement"); (B) no Person shall be
         deemed the Beneficial Owner of any shares of Common Stock that are
         Beneficially Owned by any other Person solely as a result of such
         Person's, or such other Person's service as a member of any committee
         or working group of debtholders of PageNet or the Company; and (C)
         Common Stock shall be deemed to include shares of Common Stock issuable
         upon conversion of shares of the Company's Series C Convertible
         Preferred Stock, $.01 par value per share, and shares of Common Stock
         issuable upon conversion of the Company's Series D Convertible
         Preferred Stock, $.01 par value per share, issued in the Resurgence
         Exchange. For purposes of this Agreement: (A) the PageNet Effective
         Time shall mean the Effective Time of the Merger as determined pursuant
         to the PageNet Merger Agreement and (B) the Resurgence Exchange shall
         mean the exchange by Resurgence of up to $100,000,000 in principal
         amount at maturity of the Company's 10 7/8% Senior Discount Notes Due
         2008 for shares of the Company's Series D Convertible Preferred Stock.

IN WITNESS WHEREOF, the parties have caused this Amendment No. 6 to be duly
executed and their respective corporate seals to be hereunto affixed and
attested as of the day and year first written above.


                                             ARCH COMMUNICATIONS GROUP, INC.

Attest:

  /s/ Patricia Gray                          By: /s/ J. Roy Pottle
------------------------------                   -----------------------------
Name:    Patricia Gray                       Name:   J. Roy Pottle
Title:   Secretary                           Title:  Executive Vice President
                                                     and Chief Financial Officer

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                                             THE BANK OF NEW YORK

Attest:

  /s/ John Sivertsen                         By: /s/ Eon Canzius
------------------------------                   -----------------------------
Name:    John Sivertsen                      Name:   Eon Canzius
Title:   Vice President                      Title:  Assistant Vice President

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