Anxiety is a common co-occurring problem among young people with autism spectrum disorders (ASD). Characterized by deficits in social interaction, communication problems, and stereotyped behavior and restricted interests, this group of disorders is more prevalent than previously realized. When present, anxiety may compound the social deficits of young people with ASD. Given the additional disability and common co-occurrence of anxiety in ASD, we developed a manual-based cognitive-behavioral treatment program to target anxiety symptoms as well as social skill deficits in adolescents with ASD [Multimodal Anxiety and Social Skills Intervention: MASSI]. In this paper, we describe the foundation, content, and development of MASSI. We also summarize data on treatment feasibility based on a pilot study that implemented the intervention.