The factors leading to the initial adoption of an interorganizational system (IOS) are reasonably well understood, but this is not true of the determinants of the activities performed following that decision. This paper proposes that the motivation to implement a system is the starting point for understanding the implementation process and develops a theory about the relationship between the motivation to implement an IOS system and the types of activities likely to be performed in the project. We then compare predictions against activities actually performed in three electronic data interchange (EDI) projects, and find that the patterns predicted are observed. On this basis, we assert that motivation influenced business decisions regarding which activities to conduct in each project. We finally assess the likely long-run consequences of each organization's activity pattern, noting that each motivation-based pattern brings with it a number of potential risks and opportunities that need to be managed carefully.