MASTER REAFFIRMATION OF
                      PARENT PLEDGE AND SUPPORT AGREEMENTS


         This MASTER REAFFIRMATION OF PARENT PLEDGE AND SUPPORT AGREEMENTS (this
"Reaffirmation")  is executed as of this 30th day of November,  1995 by American
Communications  Services,  Inc., a Delaware corporation (the "Parent"), in favor
of AT&T Credit Corporation, a Delaware corporation ("Lender").

                                   WITNESSETH:

         WHEREAS, American Communications Services of Louisville, Inc., American
Communication  Services of Fort Worth, Inc. and American  Communication Services
of Columbia,  Inc.,  American  Communication  Services of Greenville,  Inc., and
American  Communication Services of El Paso, Inc. (each a Delaware corporation),
entered into those certain Loan and Security  Agreements each dated respectively
as of October 16, 1994,  February 28, 1995,  June 30, 1995 and September 9, 1995
(collectively,  as so amended and as further amended,  restated or modified, the
"Loan Agreements") with Lender;

         WHEREAS,  to induce  Lender to enter  into the Loan  Agreement,  Parent
executed and delivered  those certain Parent Pledge and Support  Agreements each
dated as of October 16, 1994,  February 28, 1995, June 30, 1995 and September 9,
1995 (collectively,  as so amended and as further amended,  restated or modified
the "Pledge Agreements") in favor of the Lender;

         WHEREAS,  the parties to the Loan  Agreements  are  entering  into that
certain Master Amendment (the "Amendment") of even date herewith; and

         WHEREAS, it is a condition precedent to the effectiveness of the
Amendment that Parent execute and deliver this Reaffirmation;

         NOW, THEREFORE, for and in consideration of the foregoing and for other
good and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the Parent hereby agrees as follows:

         1.  Reaffirmation of Pledge Agreement. The Parent acknowledges that it
has reviewed the Amendment and reaffirms that the Pledge Agreements shall
continue in full force and effect in accordance with their respective terms
notwithstanding the execution and delivery of the Amendment.

         2.  Governing Law and Jurisdiction. This Reaffirmation shall be
construed in accordance with and governed by the internal laws of the State of
New Jersey, without giving effect to any conflicts of laws principles.


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         3.  Execution in Counterparts. This Reaffirmation may be executed in
any number of counterparts, each of which shall be an original, but all of which
shall together constitute one and the same agreement.

         IN WITNESS WHEREOF,  the parties hereto have caused this  Reaffirmation
to be duly executed by their duly authorized  representatives  as of the day and
year first written above.


                                                   AMERICAN COMMUNICATIONS
                                                          SERVICES, INC.

                                                   /s/ RICHARD A. KOZAK
                                                   Name:  Richard A. Kozak
                                                   Title:  President & Chief
                                                             Executive Officer


Acknowledged and agreed to
as of the day and year first
written above.

AT&T CREDIT CORPORATION

/s/ EDWARD F. GROMEK
Name: Edward F. Gromek
Title: Vice President


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