A descriptive model of variables influencing the use of an information system is presented. The model is tested with empirical data from a study of the use of a sophisticated sales information system. These results suggest three crucial factors which should be considered in developing an implementation strategy for OR/MS applications including: 1. The process of systems design 2. The impact of the system or model on individuals, work groups and the organization 3. The quality and clarity of the system or model An example is described of the design of an information system for the United Farm Workers Organizing Committee. The design strategy included a conscious effort to consider the three factors described above. A questionnaire was used in the design to measure attitudes and provide design data. A major part of the design approach was to have system users design as much of the system as possible. An attempt was also made to develop a simple and easily understood system which would work well. The success of the system is indicated from several different types of evidence and supports the significance of the three factors listed above in information system and OR/MS model implementation.