This study examined the efficacy of the school-based Program for the Education and Enrichment of Relational Skills on the social functioning of young adults with autism and cognitive deficits. The program was administered bi-weekly at a private school for students with special needs. Students' social etiquette knowledge, friendship engagement and teacher reported levels of their social functioning were assessed pre- and post-intervention. All participants experienced significantly improved knowledge of appropriate social etiquette. Further, students with cognitive deficits, but not those with autism, reported a significant increase in friendship engagement. Overall, the PEERS school curriculum benefited young adults with cognitive deficits, but the students with ASD experienced more challenges applying their new social skills outside of the program.