Parent involvement in social skills training programs for autistic children has been associated with improvement in child and family functioning. However, limited research has explored parents’ treatment experiences, which may elucidate key therapeutic elements mediating long-term maintenance of outcomes. This study examines parent perspectives on the University of California, Los Angeles Program for the Education and Enrichment of Relational Skills (PEERS®) for Preschoolers, a group-based social skills intervention for young autistic children with social challenges. Twenty-four parents reported on outcomes and participated in semi-structured interviews 1–5 years after program completion. Inductive thematic analysis was used to categorize parent responses across four domains: Parenting behaviors, Child Outcomes, Parent Perspectives, and Challenges within Treatment. Results demonstrated an overall positive impact of PEERS® for Preschoolers, with children displaying increased social competence in peer interactions and parents emphasizing greater positivity, new parenting strategies, increased understanding, and more robust community support. Mixed methods analyses revealed that parents who endorsed continued use of social coaching skills, in particular priming and preparing their child for social interactions, showed greater improvements in long-term child functioning and parenting stress. Findings validate the efficacy of PEERS® for Preschoolers, while emphasizing the value of providing strengths-based coaching and social supports to parents participating in social skills treatment for children on the autism spectrum.