Schools are the portal through which many children with autism spectrum disorder access early intervention. Collaborating with teachers can be an effective way to implement evidence-based practices. In this study, teachers learned to embed strategies from the Joint Attention, Symbolic Play, Engagement, and Regulation intervention into the standard preschool curriculum. Twelve schools with special education preschool classrooms for students with moderate to severe disabilities from under-resourced neighborhoods were randomized to augment their curriculum with Joint Attention, Symbolic Play, Engagement, and Regulation strategies or continue the standard curriculum. Teachers' strategy implementation, children's time on task, and social communication were examined before and after completing the intervention phase. Teachers in the Joint Attention, Symbolic Play, Engagement, and Regulation group implemented more Joint Attention, Symbolic Play, Engagement, and Regulation strategies than the control group after the intervention phase. Children in both groups increased time on task during teacher-led small group instruction. Children in the Joint Attention, Symbolic Play, Engagement, and Regulation group were more likely to be engaged with peers during small group instruction at the end of the intervention phase. Children from both groups improved in standardized measures of joint attention, requesting, expressive language, and receptive language. Training teachers to embed Joint Attention, Symbolic Play, Engagement, and Regulation strategies into small group instruction can help facilitate peer engagement, providing children more opportunities for peer socialization.