Supplier involvement in product development has been a widely discussed theme in recent years. Sometimes, one 'best method' for involvement, derived from studies of one particular industrial context, has been suggested. In this article, however, various forms for coordinating such involvement are distinguished, based on a study of six different product development projects. Three main approaches are formulated and discussed: project integration coordination, disconnected sub-project coordination, and ad hoc coordination. Based on the empirical study and the literature, the drivers of different types of supplier coordination are discussed. Several managerial implications are suggested related to the need to differentiate inter-organizational coordination, not only from project to project but also throughout a project. The importance of taking into account short-term, project-based drivers as well as long-term strategic objectives of supplier coordination is also discussed.