The traditional role of computer-based information systems is to provide support for individual decision making. According to this model, information is to be seen as a valuable resource for the decision maker faced with a complex task. Such a view of information systems in organizations does however fail to include such phenomena as the daily use of information for misrepresentation purposes. The conventional systems analysis methods, whether they are data- or decision-oriented, do not help in understanding the nature of organizations and their ways of processing information. The paper proposes what appears to be a more realistic approach to the analysis and design of information systems. Organizations are seen as networks of contracts which govern exchange transactions between members having only partially overlapping goals. Conflict of interests is explicitly admitted to be a factor affecting information and exchange costs. Information technology is seen as a means to streamline exchange transactions, thus enabling economic organizations to operate more efficiently. Examples are given of MIS, data base and office automation systems, where both the organization and its information system were jointly designed. These examples illustrate the power of the approach, which is based on recent research in the new institutional economics.