This study will examine the role of an adapted Cognitive Behavioral Therapy (CBT) program in treating the anxiety symptoms of children, aged 8-11, with autism and intellectual disability. A multiple-baseline design will be incorporated among the four participants who will be enrolled in baseline sessions of 3, 5, 7, and 9 respectively. Recent studies have indicated CBT as an effective treatment for children and adolescents with autism who have IQ scores in the normal range, but no study has reported the effects of CBT for people with autism and intellectual disability (i.e., IQ<70). Adaptations will consist of presenting concepts in a visual play-based format, limiting verbal demands, and simplifying higher-level concepts to meet the developmental level of participants. Successful adaptation of such a program will provide a new avenue of treatment for this population. Results will primarily be based upon session-by-session ratings from caregivers and will also include clinician and child ratings. Training includes supervision during the development and implementation of the intervention protocol, collaboration with research professors, and instruction for conducting diagnostic assessments of autism and anxiety. The research study includes development and refinement of an adapted CBT manual, training of research staff, research meetings to assess progress, implementation of the intervention, and data analysis.