Participation in this study will last 12 to 14 weeks, with follow-up visits occurring 3 and 12 months after that. Participants will be randomly assigned to receive the treatment program either immediately or after being on a wait list. The treatment program will consist of 12 to 14 weekly individual therapy sessions that teach children and adolescents about ASDs, use cognitive-behavioral interventions to address problematic thinking and acting, deliver social skills instruction, and give opportunities to practice skills—including some practice outside the clinic in naturalistic settings. Every 2 weeks, starting at Week 4, children and adolescents will also attend group sessions to discuss strategies and practice social skills. Parents of the participants will be included at the end of each individual session for several minutes. After the participants assigned to immediate treatment complete the program, participants from the wait list will be offered the treatment.