Adolescence can be a time of new and complex social challenges and individuals with Autism Spectrum Disorder (ASD) are in need of evidence-based interventions to bolster their social skills during this critical developmental period. While a number of social skill group interventions have been developed, many of these are in need of further research evidence of their effectiveness. A literature review was conducted and identified a number of strengths and weaknesses in the currently available interventions. The START group was designed to incorporate those strengths and improve upon those weaknesses. A previous pilot study of the START group indicated that it may be an effective intervention for this population. The current study expanded on this pilot study and investigated several important questions about the START group, including its effectiveness when compared to a waitlist control group and the trajectories of improvement of participants.

Nineteen adolescents with ASD participated, and a number of outcome measures were utilized to examine social change, including parent report measures, participant self-report measures, behavioral observations, and subjective ratings. The analysis comparing the treatment and control groups resulted in large effect sizes on both the primary parent and participant measures. Other measures also exhibited small to large effect sizes. These results were not found to be statistically significant, which may be attributed to the small sample size. However, the relatively large effect sizes found indicate the clinical and social significance of this intervention. The analysis of the treatment trajectories of participants indicated that most of the outcome measures exhibited statistically significant improvement after only ten weeks of intervention.

After this initial gain, the primary parent report measure continued to exhibit statistically significant improvement throughout the duration of the treatment. Other measures indicated positive but non-significant trends toward continued improvement. Possible explanations for this treatment trajectory are discussed. The clinical implications of these findings are explored, as are future research directions.