This study examined the extent to which peer mediation increased, maintained, and generalized social initiations and responses of elementary students with autism spectrum disorder as compared to their typically developing peers. A multiple-baseline across participants design was used to determine the impact of intervention. Results indicated that peer mediation increased, maintained, and generalized responses for all participants, and initiations remained stable. Additionally, all participants increased responses to levels within the range of responses demonstrated by their peer groups. Probes to assess the persistence of generalization effects were collected and analyzed.