1 EXHIBIT 23.1 CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS As independent public accountants, we hereby consent to the incorporation by reference in this Registration Statement on Form S-8 of our reports dated August 11, 1998 included in the Annual Report on Form 10-K of Aspen Technology, Inc. for the fiscal year ended June 30, 1998 and to the reference to our firm in this Registration Statement. /s/ ARTHUR ANDERSEN LLP Boston, Massachusetts June 3, 1999