Research on the user satisfaction dimension of information systems (IS) success has typically focused on the technical characteristics of the system being studied and has not emphasized user attitudes toward the system. IS researchers have noted both the omission of user attitudes and the weak theoretical foundation in research on user satisfaction with IS. Joshiís equity-implementation (E-I) model (1991), based upon equity theory, incorporates user attitudes and provides a framework for understanding satisfaction with a new IS. An extended E-I model is proposed as a theoretical foundation for investigating user satisfaction with an IS. Measures for the E-I model constructs have been developed and refined through pretests and a pilot test administered to users of enterprise resource planning (ERP) systems in three different organizations. The full data collection has been administered, and results will be presented at the conference.