This article calls for, and proposes some tenets of, model building in adolescent psychosocial development. Specifically, it is suggested that there is a need for a model that draws from the risk-protection approach, from which many prevention science approaches are drawn, and the applied developmental science perspective, from which many positive youth development approaches are drawn. The model to be built, and the integration it proposes, is based in the overlap between protective factors and developmental assets (drawn from the applied developmental science and positive youth development perspectives), as well as on the complementarity of the intrapersonal mechanisms proposed within the two perspectives. The article also poses important questions for future research and presents an empirical agenda for addressing these questions in the service of building and testing a model of adolescent psychosocial development and of integrating the prevention and positive youth development approaches to intervention and policy.