Teams and other collaborative structures have become commonplace in American schools, although historically school staff members functioned more independently from one another. In this article, we describe the growing influence of collaboration and teaming in a variety of school contexts, but focus on the empirical literature on problem-solving teams as reflecting the state of research and practice in the schools. A review of the research on problem-solving teams, using an input–mediator–outcome–input framework, provides evidence for how teaming could become more effective and efficient in this context as well as sets an agenda for what additional research is needed. Key challenges to school teams are considered next, along with recommendations for change. The first challenge is the lack of training of school staff in the key components of teaming. A second issue is the difficulty in implementing teams in the organizational context of schools.