Recess represents a rich opportunity for social development, but students with intellectual and developmental disabilities (IDD) often do not fully realize these benefits. In this systematic review, we review 37 experimental studies in which students with IDD received interventions designed to improve social outcomes at recess. Overall, these studies provide strong scientific evidence that focused intervention can produce medium to large effects on peer interaction and peer play. A subset of studies reported effects on social skills and social status, although the presence and magnitude of effects was variable. Studies tended to focus on students with autism who did not have intellectual disability and involved a combination of classroom-based social skills instruction and support on the playground from peers or adults. We recommend that special educators deliver this combination of strategies to students with autism. Further research is needed for students with intellectual disability or multiple disabilities.