This action research project was conducted to explore the effects of peer-mediation on social-emotional development and self-regulation in students aged three to five. Throughout the process, the teacher received professional coaching from a LEAP coach from the University of Denver as well as coaching from AEA staff members with background in autism and early intervention. Peer mediated strategies were introduced initially in October of 2018; during the research, the teacher focused solely on one strategy. Prior to the research, two strategies had been implemented and coached to fidelity. Quantitative data was collected from tracking and monitoring logs and researcher behavior in the form of Teaching Strategies Gold. The data was entered in a table and was used to determine if social-emotional skills (referencing self-regulation, entering social settings and positive interactions with peers in the form of getting attention, sharing or requesting) increased as a result of the peer-mediated strategies. After analyzing the data and teacher interviews, it was determined that the implementation of peer-mediated strategies had a positive effect on social-emotional growth.