As filed with the Securities and Exchange Commission on October 19, 2001
                                                      Registration No. 333-_____


                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM S-8

                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933

                             ASPEN TECHNOLOGY, INC.
             (Exact Name of Registrant as Specified in Its Charter)

         Delaware                                         04-2739697
(State or Other Jurisdiction of                        (I.R.S. Employer
Incorporation or Organization)                        Identification No.)

Ten Canal Park, Cambridge, Massachusetts                    02141
(Address of Principal Executive Offices)                  (Zip Code)

                             2001 Stock Option Plan
                            (Full Title of the Plan)

                                Lawrence B. Evans
   Chairman of the Board of Directors, President and Chief Executive Officer
                             Aspen Technology, Inc.
                                 Ten Canal Park
                         Cambridge, Massachusetts 02141
                     (Name and Address of Agent For Service)
                                 (617) 949-1000
          (Telephone Number, Including Area Code, of Agent For Service)


                         CALCULATION OF REGISTRATION FEE



================================================================================================================
Title of Securities                                Proposed Maximum       Proposed Maximum
to be  Registered      Amount to be Registered    Offering Price Per     Aggregate Offering         Amount of
                                                       Share                  Price             Registration Fee
----------------------------------------------------------------------------------------------------------------
                                                                                       
Common Stock, $0.10
par value per share       4,000,000 shares            $11.82(1)            $47,280,000(1)          $11,820.00
================================================================================================================


(1)  Estimated solely for the purpose of calculating the registration fee
     pursuant to Rules 457(c) and 457(h) of the Securities Act of 1933, as
     amended, and based upon the average of the high and low prices of the
     Registrant's Common Stock as reported on the Nasdaq National Market on
     October 15, 2001.



                                     PART I
              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

     ITEM 1. PLAN INFORMATION.

     The information required by Item 1 is included in documents sent or given
to participants in the plans covered by this registration statement pursuant to
Rule 428(b)(1) of the Securities Act of 1933, as amended (the "Securities Act").

     ITEM 2. REGISTRANT INFORMATION AND EMPLOYEE PLAN ANNUAL INFORMATION.

     The written statement required by Item 2 is included in documents sent or
given to participants in the plans covered by this registration statement
pursuant to Rule 428(b)(1) of the Securities Act.

                                     PART II
               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

     ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.

     The registrant is subject to the informational and reporting requirements
of Sections 13(a), 14, and 15(d) of the Securities Exchange Act of 1934, as
amended (the "Exchange Act"), and in accordance therewith files reports, proxy
statements and other information with the Securities and Exchange Commission
(the "Commission"). The following documents, which are on file with the
Commission, are incorporated in this registration statement by reference:

     (a)  The registrant's latest annual report filed pursuant to Section 13(a)
or 15(d) of the Exchange Act or the latest prospectus filed pursuant to Rule
424(b) under the Securities Act that contains audited financial statements for
the registrant's latest fiscal year for which such statements have been filed.

     (b)  All other reports filed pursuant to Section 13(a) or 15(d) of the
Exchange Act since the end of the fiscal year covered by the document referred
to in (a) above.

     (c)  The description of the securities contained in the registrant's
registration statement on Form 8-A filed under the Exchange Act, including any
amendment or report filed for the purpose of updating such description.

     All documents subsequently filed by the registrant pursuant to Sections
13(a), 13(c), 14 and 15(d) of the Exchange Act, prior to the filing of a
post-effective amendment which indicates that all securities offered hereby have
been sold or which deregisters all securities then remaining unsold, shall be
deemed to be incorporated by reference in this registration statement and to be
part hereof from the date of the filing of such documents. Any statement
contained in a document incorporated or deemed to be incorporated by reference
herein shall be deemed to be modified or superseded for the purposes of this
registration statement to the extent that a statement contained herein or in any
other subsequently filed document which also is or is deemed to be incorporated
by reference herein modifies or supersedes such statement. Any statement so
modified or superseded shall not be deemed, except as so modified or superseded,
to constitute a part of this registration statement.





     ITEM 4. DESCRIPTION OF SECURITIES.

     Not applicable.

     ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL.

     Not applicable.

     ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS.

     Article SEVENTH of the Registrant's Certificate of Incorporation, as
amended (the "Certificate of Incorporation"), provides that no director of the
Registrant shall be personally liable for any monetary damages for any breach of
fiduciary duty as a director, except to the extent that the Delaware General
Corporation Law prohibits the elimination or limitation of liability of
directors for breach of fiduciary duty.

     Article EIGHTH of the Certificate of Incorporation provides that a director
or officer of the Registrant shall be indemnified by the Registrant against:

     (a)  all expenses (including attorneys' fees), judgments, fines and amounts
paid in settlement incurred in connection with any litigation or other legal
proceeding (other than an action by or in the right of the Registrant) brought
against him or her by virtue of his or her position as a director or officer of
the Registrant if he or she acted or not opposed to, the best interests of the
Registrant, and, with respect to any criminal action or proceeding, had no
reasonable cause to believe his or her conduct was unlawful; and

     (b)  all expenses (including attorneys' fees) and amounts paid in
settlement incurred in connection with any action by or in the right of the
Registrant brought against him or her by virtue of his or her position as a
director or officer of the Registrant if he or she acted in good faith and in a
manner he or she reasonably believed to be in, or not opposed to, the best
interests of the Registrant, except that no indemnification shall be made with
respect to any matter as to which such person shall have been adjudged to be
liable to the Registrant, unless a court determines that, despite such
adjudication but in view of all of the circumstances, he or she is entitled to
indemnification of such expenses.

     Notwithstanding the foregoing, to the extent that a director or officer has
been successful, on the merits or otherwise, including the dismissal of an
action without prejudice, he or she is required to be indemnified by the
Registrant against all expenses (including attorneys' fees) incurred in
connection therewith. Expenses shall be advanced to a director or officer at his
or her request, provided that he or she undertakes to repay the amount advanced
if it is ultimately determined that he or she is not entitled to indemnification
for such expenses.

     Indemnification is required to be made unless the Registrant determines
that the applicable standard of conduct required for indemnification has not
been met. In the event of a determination by the Registrant that the director or
officer did not meet the applicable standard of conduct required for
indemnification, or if the Registrant fails to make an indemnification payment
within sixty days after such payment is claimed by such person, such person is
permitted to petition the court to make an independent determination as to
whether such person is entitled to indemnification. As a condition precedent to
the right of indemnification, the director or officer must give the Registrant
notice of the action for which indemnity is sought and the Registrant has the
right to participate in such action or assume the defense thereof.


     Article EIGHTH of the Certificate of Incorporation further provides that
the indemnification provided therein is not exclusive, and provides that in the
event that the Delaware General Corporation Law is amended to expand the
indemnification permitted to directors or officers the Registrant must indemnify
those persons to the fullest extent permitted by such law as so amended.

     Section 145 of the Delaware General Corporation Law provides that a
corporation has the power to indemnify a director, officer, employee or agent of
the corporation and certain other persons serving at the request of the
corporation in related capacities against amounts paid and expenses incurred in
connection with an action or proceeding to which he or she is or is threatened
to be made a party by reason of such position, if such person shall have acted
in good faith and in a manner he or she reasonably believed to be in or not
opposed to the best interests of the corporation, and, in any criminal
proceeding, if such person had no reasonable cause to believe his or her conduct
was unlawful; provided that, in the case of actions brought by or in the right
of the corporation, no indemnification shall be made with respect to any matter
as to which such person shall have been adjudged to be liable to the corporation
unless and only to the extent that the adjudicating court determines that such
indemnification is proper under the circumstances.

     The Registrant maintains a directors' and officers' insurance policy that
covers certain liabilities of directors and officers of the Registrant,
including liabilities under the Securities Act of 1933. The Registrant maintains
a general liability insurance policy that covers certain liabilities of
directors and officers of the Registrant arising out of claims based on acts or
omissions in their capacities as directors or officers.



     ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.

     Not applicable.

     ITEM 8. EXHIBITS.

     The Exhibit Index immediately preceding the exhibits is incorporated herein
by reference.

     ITEM 9. UNDERTAKINGS.

     1.   Item 512(a) of Regulation S-K. The undersigned registrant hereby
undertakes:


          (1)  To file, during any period in which offers or sales are being
     made, a post-effective amendment to this registration statement:

               (i)  To include any prospectus required by Section 10(a)(3) of
     the Securities Act;

               (ii) To reflect in the prospectus any facts or events arising
     after the effective date of the registration statement (or the most recent
     post-effective amendment thereof) which, individually or in the aggregate,
     represent a fundamental change in the information set forth in the
     registration statement; and

               (iii) To include any material information with respect to the
     plan of distribution not previously disclosed in the registration statement
     or any material change to such information in the registration statement;

     provided, however, that paragraphs (i) and (ii) do not apply if the
     information required to be included in a post-effective amendment by those
     paragraphs is contained in periodic reports filed with or furnished to the
     Commission by the registrant pursuant to Section 13 or Section 15(d) of the
     Exchange Act that are incorporated by reference in the registration
     statement.

          (2)  That, for the purpose of determining any liability under the
     Securities Act, each such post-effective amendment shall be deemed to be a
     new registration statement relating to the securities offered therein, and
     the offering of such securities at that time shall be deemed to be the
     initial bona fide offering thereof.

          (3)  To remove from registration by means of a post-effective
     amendment any of the securities being registered which remain unsold at the
     termination of the offering.

     2.   Item 512(b) of Regulation S-K. The undersigned registrant hereby
undertakes that, for purposes of determining any liability under the Securities
Act, each filing of the registrant's annual report pursuant to Section 13(a) or
Section 15(d) of the Exchange Act that is incorporated by reference in the
registration statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.




     3.   Item 512(h) of Regulation S-K. Insofar as indemnification for
liabilities arising under the Securities Act may be permitted to directors,
officers and controlling persons of the registrant pursuant to the foregoing
provisions, or otherwise, the registrant has been advised that in the opinion of
the Securities and Exchange Commission such indemnification is against public
policy as expressed in the Securities Act and is, therefore, unenforceable. In
the event that a claim for indemnification against such liabilities (other than
the payment by the registrant of expenses incurred or paid by a director,
officer or controlling person of the registrant in the successful defense of any
action, suit or proceeding) is asserted by such director, officer or controlling
person in connection with the securities being registered, the registrant will,
unless in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the
Securities Act and will be governed by the final adjudication of such issue.




                                   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 City of Cambridge, Massachusetts on this seventeenth
day of October, 2001.

                                Aspen Technology, Inc.

                                By: /s/ Lawrence B. Evans
                                   ---------------------------------------------
                                   Lawrence B. Evans
                                   Chairman of the Board of Directors, President
                                   and Chief Executive Officer


                        POWER OF ATTORNEY AND SIGNATURES

     We, the undersigned officers and directors of Aspen Technology, Inc.,
hereby severally constitute and appoint Lawrence B. Evans, Lisa W. Zappala and
Michael J. Muscatello, 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 subsequent amendments to said registration
statement, and generally to do all such things in our names and on our behalf in
our capacities as officers and directors to enable Aspen Technology, Inc. to
comply with the provisions of the Securities Act of 1933, as amended, 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.

     Pursuant to the requirements of the Securities Act of 1933, this
registration statement has been signed by the following persons in the
capacities on this seventeenth day of October, 2001.

      SIGNATURE                                      TITLE

/s/ Lawrence B. Evans          Chairman of the Board of Directors, President and
-------------------------      Chief Executive Officer (Principal executive
Lawrence B. Evans              officer)



/s/ Lisa W. Zappala            Senior Vice President and Chief Financial Officer
-------------------------      (Principal financial and accounting officer)
Lisa W. Zappala



                                Director
-------------------------
Joseph F. Boston


/s/ Gresham T. Brebach          Director
-------------------------
Gresham T. Brebach


/s/ Douglas R. Brown            Director
-------------------------
Douglas R. Brown


/s/ Stephen L. Brown            Director
-------------------------
Stephen L. Brown


/s/ Stephen M. Jennings         Director
-------------------------
Stephen M. Jennings


/s/ Joan C. McArdle             Director
-------------------------
Joan C. McArdle






                                INDEX TO EXHIBITS

Number       Description
------       ------------

4.1(1)       Certificate of Incorporation of the Registrant

4.2(2)       By-Laws of the Registrant

4.3(2)       Rights Agreement dated as of October 9, 1997 between the Registrant
             and American Stock Transfer and Trust Company, as rights agent

5.1*         Opinion of Hale and Dorr LLP, counsel to the Registrant

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 on the signature pages of this
             registration statement)

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

*    Filed herewith

(1)  Previously filed with the Securities and Exchange Commission as an Exhibit
     to the Registrant's Form 8-K filed March 27, 1998 and incorporated herein
     by reference.

(2)  Previously filed with the Securities and Exchange Commission as an Exhibit
     to the Registrant's Registration Statement on Form 8-A (filed on September
     13, 1994), as amended by Amendment No 1 thereto (filed on June 12, 1998),
     and incorporated herein by reference.