Background/Objective: Researchers have traditionally reported that individuals with Down syndrome possess a strength in their social development, yet the opposite occurs with Asperger's syndrome. Based on this premise, we sought to assess effectiveness of the social skills training program. Method: Thirty adolescents aged 11 to 14 years with Down syndrome and Asperger's syndrome participated in the study. Results: Significant differences between both groups were detected in the posttreatment measures and a connection was found between adolescents' learning potential and the benefits gained. Conclusions: The training program is effective at improving the social skills under evaluation in adolescents with Down syndrome; however, this benefit is greater among adolescents with Asperger's syndrome.