Exhibit 10.47

April 1, 2002

Mary A. Palermo
Co-Chief Operating Officer
Aspen Technology, Inc.
Ten Canal Park
Cambridge, MA 02141


Dear Mary:

In consideration of your position, assisting with the transition of the Company
to a new organization, and future work, I propose the following terms of
employment:


COMPENSATION AND EMPLOYMENT

     1)   You will continue to be employed by AspenTech as Executive Vice
          President and Co-Chief Operating Officer at least until September 30,
          2002. During this time you will report to Larry Evans, Chairman. You
          will focus on execution of our Aspen 2002 Strategy and implementing
          the organizational changes. If we acquire Denver, this will be an
          important component of your responsibilities and activities.

     2)   You will continue at your present level of compensation through FY02.
          You will be eligible for a bonus for FY02 on the same basis as the
          other comparable members of the executive management team. You will be
          eligible for a salary increase at such time as any other members of
          the executive management team. You will continue to receive grants of
          stock options comparable to other members of the executive management
          period.

     3)   Effective October 1, 2002 you will work in business development for
          AspenTech for a period of 15 months until December 31, 2003 ("BD
          Period"). During that time you will continue to be paid at your
          present base salary. Your stock options will continue to vest during
          this period. AspenTech will continue to provide an office, secretarial
          assistance, telephone, and email account during this period. Your
          responsibilities will be primarily to be provide advice, guidance and
          business development services, but not to undertake major projects
          that would involve a significant commitment of effort.

     4)   The Company and you may, by mutual agreement, decide that you will
          remain in your present position or a new position for an extended
          period beyond September 30, 2002. If this happens, your rate of pay
          and bonus opportunity for this extended period will be determined by
          mutual agreement, but will not be reduced, and the 15-month BD Period
          will begin immediately after the last day of such extended employment
          as agreed to under this paragraph 4.

     5)   On or before the end of the BD Period, the Company and you may, by
          mutual agreement, decide that you will remain in a business
          development position beyond December 31, 2003. In such event your rate
          of pay will be determined by mutual agreement and your stock options
          would continue to vest during such extended period.

     6)   You agree to be fully supportive of the new organization and
          management and to do your best to help us achieve an enthusiastic
          transition.




     7)   You agree to the terms and conditions of Addendum A to this letter on
          your non-compete, non-solicitation, and confidentiality agreements,
          and that such obligations will be in force and effect for the later of
          the period ending December 31, 2004, or two years after termination of
          employment.

     8)   Your compensation, benefits and employment will be structured to
          achieve as favorable tax and employment treatment as is possible and
          not otherwise materially detrimental to the interests of the Company.

This Agreement shall be governed by and construed in accordance with the laws of
the Commonwealth of Massachusetts. The Federal and State Courts in the
Commonwealth of Massachusetts shall have exclusive jurisdiction over all claims
brought in connection with this Agreement.

By signing a copy of this letter you hereby indicate your agreement to the terms
and conditions set out in this letter and Addendum A.


                                  ASPEN TECHNOLOGY, INC.


                                  By: /s/ Lawrence B. Evans
                                      --------------------------------
                                  Name:       Lawrence B. Evans
                                       -------------------------------

                                  Title:  Chairman and Chief Executive Officer
                                        ---------------------------------------



Accepted and Agreed to this ___ day of _______, 2002.


/s/ Mary A. Palermo
- ---------------------------
Mary A. Palermo




                                   Addendum A
               NON-COMPETE, NON-SOLICITATION, AND CONFIDENTIALITY
               --------------------------------------------------

AGREEMENT NOT TO COMPETE. Mary A. Palermo (the "Employee") agrees that, while
serving as an Employee of the Company, she will not serve as an employee or
director of any business entity other than the Company and its affiliates that
is a competitor of the Company, but may serve as a director of a reasonable
number of not-for-profit corporations and may devote a reasonable amount of time
to charitable and community service. In consideration of the payments and
agreements hereunder, the Employee shall not solicit the Company's, or its
affiliates' or subsidiaries' (collectively, the "AspenTech Companies") customers
with whom Employee has dealt during the one year prior to the Termination Date,
either (i) to cease to do business with the AspenTech Companies, or (ii) to do
business with any other firm, partnership, or entity, in actual or proposed
competition with the AspenTech Companies. The Employee may hold stock or a
limited partnership interest of 5% or less in any publicly traded entity without
violating this Agreement.

AGREEMENT NOT TO SOLICIT. In consideration of the payments and agreements
hereunder, the Employee shall not solicit any employee of the AspenTech
Companies to leave such employment or to provide services to the Employee or any
other business entity, whether or not the Employee is employed by such entity,
or the Employee has a material financial interest therein.

CONFIDENTIAL INFORMATION: NON-DISCLOSURE. Employee acknowledges that the
business of the AspenTech Companies is highly competitive and that the Company
has provided and will provide Employee with access to Confidential Information
relating to the business of the AspenTech Companies. "Confidential Information"
means and includes the AspenTech Companies' confidential and/or proprietary
information and/or trade secrets that have been developed or used and/or will be
developed and that cannot be obtained readily by third parties from outside
sources. Confidential Information includes, by way of example and without
limitation, the following: information regarding customers, employees,
contractors, and the industry not generally known to the public; strategies,
methods, books, records, and documents; technical information concerning
products, equipment, services, and processes; procurement procedures and pricing
techniques; the names of and other information concerning customers, investors,
and business affiliates (such as contact name, service provided, pricing for
that customer, amount of services used, credit and financial data, and/or other
information relating to the AspenTech Companies' relationship with that
customer); pricing strategies; plans and strategies for expansion or
acquisitions; budgets; customer lists; electronic databases; models;
specifications; computer programs; internal business records; contracts
benefiting or obligating the AspenTech Companies; bids or proposals submitted to
any third party; technologies and methods; training methods and training
processes; organizational structure; salaries of personnel; payment amounts or
rates paid to consultants or other service providers; and other such
confidential or proprietary information. Employee acknowledges that this
Confidential Information constitutes a valuable, special, and unique asset used
by the AspenTech Companies in their business to obtain a competitive advantage
over their competitors. Employee further acknowledges that protection of such
Confidential Information against unauthorized disclosure and use is of critical
importance to the AspenTech Companies in maintaining their competitive position.
Confidential Information shall not include any information that is contained in
a printed publication or is or becomes publicly known through no wrongful act or
failure to act on the part of the Employee.

Employee agrees that Employee will not, at any time during or after Employee's
employment with Company, make any unauthorized disclosure of any Confidential
Information of the AspenTech Companies, or make any use thereof, except in the
carrying out of her employment responsibilities hereunder. Employee also agrees
to preserve and protect the confidentiality of third party Confidential
Information to the same extent, and on the same basis, as the AspenTech
Companies' Confidential Information.