When my daughter was diagnosed with Pdd-Nos, her doctor recommended 25+ hours of therapeutic intervention per week, including Applied Behavior Analysis (ABA). In shock, I asked how I would know if an ABA therapist was good or not. She recommended that I purchase Behavioral Intervention for Young Children With Autism by Catherine Maurice. This book was literally a life saver. It taught me not only how to monitor my daughter's therapy, but also how to do it. At times, it is pretty technical, but skip those parts for later and read through as much as you can.