The establishment of reciprocal friendships is a challenge for many individuals with autism spectrum disorder (ASD). Social interaction difficulties emerge early, persist throughout development, and have widespread functional impact. As such, interventions focused on social functioning are needed in early intervention programs. This two-part study evaluated the outcomes of a parent-assisted social skills training (SST) program for young children with ASD. The intervention is a downward extension of the Program for the Education and Enrichment of Relational Skills (PEERS(R)), which is one of the few evidence-based SST programs for adolescents and young adults with ASD. Modifications included developmentally appropriate social skills, greater parent involvement, and behavioral strategies embedded in play-based activities. Results reveal improvements in parent ratings of social responsiveness, social cognition, and social motivation, as well as decreased (a) restricted/repetitive behaviors and interests and (b) problem behaviors. Results are promising and encourage further evaluation of this SST curriculum.