The purpose of this study was to investigate the effects of peer intervention on the social interactions of children with autism spectrum disorder (ASD). In this model, a speech-language pathologist and three early childhood educators trained typically developing peers to engage children with ASD in play. Three preschool children with ASD and six peers participated. The peer intervention took place in early childhood classrooms during play sessions with blocks and play dough. A single-subject multiple baseline design across subjects was used to determine the effects of the intervention. All three children with ASD demonstrated significant gains in the number and length of their interactions with peers, and maintained their gains. The results provided preliminary evidence supporting this model of intervention. Treatment fidelity and social validation measures are documented.