This study evaluates the efficacy of a school-based social cognitive intervention for children with autism. Seventy-four children and adolescents were taught visually scaffolded, theory of mind-based social skills program. Using a mixed-methods approach, children's social competence was assessed at pre-test and post-test. Compared to a waitlist control group, children in the intervention group demonstrated significantly greater gains on theory-of-mind and social skill measures. Focus groups and interviews were conducted to explore parents' views and generalization of children's social skills across settings. Children's social participation exhibited improvement in home, community, and school settings. The study findings offer promising evidence for a cost-effective program and support of the school-based social skills intervention for children with ASD in Hong Kong context.