Social competence is an essential skill that can be promoted in inclusive high school classrooms. For high school students with developmental disabilities, peer-mediated interventions have shown promise for increasing social communication with feasible implementation. This study focused on increasing the appropriate peer interactions of three high school students with autism or intellectual disabilities in inclusive general education classrooms. We used a single-case multiple probe design to evaluate the effectiveness of a low-intensity peer-mediated intervention delivered by a paraprofessional to six peer partners. Our visual analysis of the data resulted in determining a functional relation between the intervention and students' appropriate peer interactions. The peer partners and educators found the goals, procedures, and outcomes to be beneficial, important, and practical. We also discuss the implications, limitations, and ideas for future research.