Extant research on interorganizational relationships has generally considered the propensity of organizations to collaborate and interorganizational rivalry as antithetic behaviours. In this paper we try to reconcile apparently contentious theoretical views on the relationship between interorganizational collaboration and competition, and propose a model that predicts the existence of a non-monotonic effect of similarity in resource dependence profiles on the propensity of interdependent organizations to collaborate and exchange resources. We test our theoretical argument by using data that we have collected on 91 health care organizations serving more than five million residents in one of the largest Italian geographical regions. Controlli...