1 EXHIBIT 23.1 CONSENT OF INDEPENDENT ACCOUNTANTS We hereby consent to the incorporation by reference in the Registration Statement on Form S-8 (No. 333-85363) of OneSource Information Services, Inc. of our report dated October 22, 1999, relating to the financial statements of Corporate Technology Information Services, Inc., appearing in Amendment 1 to the Current Report in Form 8-K/A of OneSource Information Services, Inc. dated December 13, 1999. PricewaterhouseCoopers LLP Boston, Massachusetts December 13, 1999 23