Social communication is a key component in building and maintaining friendships. However, students with autism spectrum disorder and intellectual disability often exhibit deficits in communication behaviors. Peer-mediated interventions are an evidence-based practice in increasing social communication skills for elementary and middle school students. Systematic instruction has been used as an intervention for both academic and functional skills. This study utilized a multiple probe design across students to assess the effectiveness of training two high school aged peer mediators to implement a system of least prompts strategy during a leisure activity to elicit social communication behaviors from four same age peers with disabilities. Results showed increases in initiations and independent responses when system of least prompts was used effectively by peer mediators. Future implications are discussed.