Despite reports of high anxiety in children with autism spectrum disorders (ASD), there is controversy regarding differential diagnosis of ASD symptoms and anxiety symptoms. This study examined 88 children, aged 7–11 years, with ASD referred for concerns about anxiety. A multitrait-(social anxiety, separation anxiety, overall anxiety severity, and overall ASD severity), multimethod-(diagnostic interviews, parent-, and child-based measures) analysis was conducted. Results from structural equation modeling suggest statistical discrimination between anxiety and ASD severity and convergence among differing reports of two of the anxiety subdomains (separation anxiety and overall anxiety). These findings suggest that anxiety symptoms experienced by children with ASD are separate from ASD symptom severity and may instead reflect anxiety syndromes (e.g., separation anxiety) similar to those that occur in typically developing children.