information system, as a primary criterion for system success, and three secondary criteria--profitabi lity, contribution to user performance, and user satisfaction. The information system which served as a vehicle for the study was an implementation of the Project Evaluation and Review Technique (PERT) in a large research and development organization. Project managers in the organization, and their assistbnts, constituted the population of potential users. The data suggest that use is highly dependent on the contribution of the system to user performance. Degree of use, therefore, is a ' convenient surrogate for the less easily measured concept of system success.