Sharing of patient outcome data among hospitals hastened the evolution of continuous quality improve ment at Voluntary Hospitals of American/Pennsyl vania (VHA/PA) to a focus on learning from the best: clinical benchmarking. Analysis of VHA/PA MedisGroups comparative outcome data showed sig nificant variation. In the first study, variations from 3 to 25% normal appendectomy rates were noted. A second study on primary and secondary cesarean sec tion rates again showed variation in outcomes. A study of the benchmark hospitals showed character istics, specific to those institutions, that resulted in excellent outcomes. To quantify best processes, VHA/ PA has embarked on a clinical benchmarking project with the assistance of MediQual Systems, Inc.