This study examined the treatment efficacy of PEERS®; (Program for the Education and Enrichment of Relational Skills) among Chinese adolescents with autism spectrum disorder (ASD) in Hong Kong. The original PEERS®; manual was translated into Chinese, and cultural adjustments were made according to a survey among 209 local adolescents in the general population. 72 high-functioning adolescents with ASD were randomly assigned to a treatment or waitlist control group. The 14-week parent-assisted training significantly improved social skills knowledge and social functioning, and also reduced autistic mannerisms. Treatment outcomes were maintained for 3 months after training and replicated in the control group after delayed treatment. The present study represents one of the few randomized controlled trials on PEERS® conducted outside North America. [Copyright of Journal of Autism and Developmental Disorders is the property of Springer Science & Business Media. Full article may be available at the publisher's website: http://dx.doi.org/10.1007/s10803-018-3728-1]