The concept of psychological ownership is employed in order to enhance our understanding of the relationship between users and information technology professionals and to describe the IT/business process relationship. We use co-ownership to signify a complementary relationship in which users are involved in IT while IT professionals are simultaneously involved in business processes. In an initial study, interviews at four organizations suggest that co-ownership explains information systems’ success and top-rated returns from IT investments. In a second study, we are developing a measure of co-ownership and testing its effect on IT value and performance through a large-scale survey.