The purpose of this study was to determine the effectiveness of a peer mediated intervention to increase social communication acts of preschool children with autism spectrum disorder (ASD). Utilizing a single-subject A-B design across four peer dyads, I examined the overall effectiveness of the intervention in relation to specific nonverbal, verbal, and play behaviors and examine the generalization of social communication acts outside of the intervention period. The study participants consisted of four preschool children with ASD and one typically developing peer partner for each child with ASD. All participants attended integrated preschool settings. Intervention results were reported using visual analysis and participant effect size. The intervention showed small significant increases in some areas of nonverbal interactions, interactive play, and verbal interactions for some of the peer dyads, but not all. Strong levels of implementation fidelity and social validity were also reported. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]