Autism spectrum disorders affect as many as 1 out of 88 children and are related to significant impairment in social, adaptive, and school functioning. Co-occurring conditions, such as anxiety, are common and may cause substantial distress and impairment beyond that caused by the autism diagnosis. Many children with anxiety disorders, especially those on the autism spectrum, do not receive evidence based treatment, which has fueled the development and evaluation of cognitive-behavioral therapy (CBT). Accordingly, we are proposing a randomized controlled trial to examine the efficacy of exposure based CBT that heavily incorporates parents (EF-CBT) relative to a TAU condition (TAU) in 50 youth ages 6-12 years with ASD and comorbid anxiety disorder(s).