Individuals on the autism spectrum often require additional support in the area of social communication. Peer mediated interventions target these areas by incorporating peers into the intervention. To date, most studies have focused on selecting one or two peers as models or peer interventionists with only a few studies implementing a class-wide intervention. This study implemented a class-wide intervention combining instruction on autism spectrum disorder: Stay, Play, Talk, and a group reinforcement contingency to increase autism knowledge, peer attitudes toward a focus student on the autism spectrum, and social engagement between peers and a focus student on the autism spectrum. The participants were from three kindergarten classes, with focus students on the autism spectrum. Participants demonstrated significant increases in their autism knowledge from pre-test to post-test. There were not significant differences in attitudes towards the focus student from pre-intervention to post-intervention measures. Finally, no changes were observed in social engagement following the introduction of the intervention. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]