Inclusion Criteria:  ASD criteria on Social Communication Questionnaire-Lifetime and Autism Diagnostic Interview-Revised. Between ages of 3 and 9 years exhibiting clinically significant levels of repetitive behavior (Score >26 on Repetitive Behavior Scales-Revised prior clinical or medical diagnosis of autism spectrum disorder  Exclusion Criteria:  diagnosed comorbid genetic disorder known to associated with increased symptom severity child engages in serious self-injurious behavior with intensity or frequency that warrants hospitalization change in psychotropic medications within last 6 weeks child already receives >20hours per week of home-based ABA services