Children with autism spectrum disorders (ASD) face pervasive challenges in symbolic and social play development. The Integrated Play Groups (IPG) model provides intensive guidance for children with ASD to participate with typical peers in mutually engaging experiences in natural settings. This study examined the effects of a 12-week IPG intervention on the symbolic and social play of 48 children with ASD using a repeated measures design. The findings revealed significant gains in symbolic and social play that generalized to unsupported play with unfamiliar peers. Consistent with prior studies, the outcomes provide robust and compelling evidence that further validate the efficacy of the IPG model. Theoretical and practical implications for maximizing children's developmental potential and social inclusion in play are discussed.