In this article we provide a review of theory and research on the use of peers to influence learning outcomes in physical education. First, we summarize the empirical literature on the use of peers in general education. Next, Piaget's equilibration theory, Vygotsky's sociocultural theory, and Skinner's behavior analytic theory are discussed with particular reference to their implications for the use of peers in educational settings. This is followed by a review of findings from research studies using peers in physical education settings and includes suggestions for future research. We conclude with a discussion of implications for practice.