This paper compares the effectiveness of two mechanisms for governing the relationship between an information systems development team and the new system's users. This relationship is traditionally governed using phased commitments and user involvement. Drawing on the organizational economics literature, the paper proposes a new view in which a project is characterized as a transaction, or an exchange, between IS and the users. Two alternatives for governing this exchange, one based on explicit, classical contracting and the other relying more on implicit, social contracting, are hypothesized to be differentially effective in governing exchanges of low or high difficulty, respectively. The model is explored in a field study at a single site and found to be supported, indicating that more rigorous tests of the model are warranted.