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PROSPECTUS SUPPLEMENT NO. 8                     FILED PURSUANT TO RULE 424(b)(3)
TO PROSPECTUS DATED DECEMBER 10, 1998           REGISTRATION NO. 333-63439


                                   $86,250,000

                             ASPEN TECHNOLOGY, INC.

            5 1/4% CONVERTIBLE SUBORDINATED DEBENTURES DUE JUNE 15, 2005


     This Prospectus Supplement supplements the information we provided in our
December 10, 1998 Prospectus relating to our 5 1/4% Convertible Subordinated
Debentures due June 15, 2005 and the shares of our common stock that we must
issue upon conversion of those Debentures, and in our Prospectus Supplements No.
1, No. 2, No. 3, No. 4, No. 5, No. 6 and No. 7. This Prospectus Supplement is
not complete without the supplemented Prospectus, and we have not authorized
anyone to deliver or use this Prospectus Supplement without the supplemented
Prospectus.

     In this Prospectus Supplement, we use capitalized terms that we defined in
the Prospectus. You should read the Prospectus to understand those terms. Unless
we indicate otherwise, the information in this Prospectus Supplement is as of
November 16, 1999.

     We are providing this Prospectus Supplement to update the following
information to the table in the Prospectus under the caption "Selling
Securityholders":



                                    PRINCIPAL AMOUNT OF                    SHARES OF COMMON                     SHARES OF COMMON
                                  DEBENTURES BENEFICIALLY                 STOCK BENEFICIALLY                   STOCK BENEFICIALLY
                                   OWNED PRIOR TO THE                     OWNED PRIOR TO THE    SHARES OF       OWNED AFTER THE
                                          OFFERING          AMOUNT OF         OFFERING            COMMON           OFFERING
                                  -----------------------  DEBENTURES    --------- ----------     STOCK       --------------------
    SELLING SECURITYHOLDER          NUMBER     PERCENT(1)  OFFERED(2)    NUMBER(3) PERCENT(4)    OFFERED(3)    NUMBER   PERCENT(4)
    ----------------------          ------     ----------  ----------    --------------------   -----------   --------  ----------
                                                                                                   
Peoples Benefit Life Insurance
Company........................  $2,000,000      2.3%      $2,000,000     37,758      *            37,758         --       --
c/o Camden Asset Management, L.P.
2049 Century Park East, Suite 330
Los Angeles, CA 90067


- ------------
*    Less than one percent.
(1)  For purposes of this Prospectus Supplement only, we have calculated this
     percentage on the basis of $86,250,000 aggregate principal amount of
     Debentures outstanding on November 16, 1999.
(2)  This Selling Securityholder has indicated that it may offer all of the
     Debentures that it owns. As a result, no Debentures will be owned after the
     offering.
(3)  For purposes of this Prospectus Supplement only, we have calculated this
     number using the conversion rate described on the front cover page of the
     Prospectus.
(4)  For purposes of this Prospectus Supplement only, we have calculated this
     percentage on the basis of 25,196,988 shares of common stock outstanding on
     November 16, 1999.


          THE DATE OF THIS PROSPECTUS SUPPLEMENT IS NOVEMBER 18, 1999.