A social skills training (SST) for high-functioning children with autism spectrum disorders (ASD) was evaluated in an outpatient setting using a combined between- and within-subject design in which SST and a waiting list condition were compared. According to parents and teachers, the SST produced greater improvement of social skills than the waiting list, and these effects were maintained at 3 months follow-up. No between-group effects were found for loneliness, although in general scores on this outcome measure decreased from pre- to follow-up. The effects of SST were unaffected by social anxiety, ADHD symptoms, Theory of Mind, or desire for social interaction. Altogether, SST seems an effective intervention for high-functioning children with ASD that can be applied in daily clinical practice.