High rates of anxiety and depression are reported among youth with autism spectrum disorders. These conditions are generally assessed using measures validated for typically developing youth. Few studies have investigated their validity for autism spectrum disorders, which is crucial for accurate assessment and the provision of proper treatment. The Revised Children's Anxiety and Depression Scale was evaluated with 67 youth with autism spectrum disorders to examine its utility in measuring anxiety and depression in this population. Parents and children (aged 11-15 years) referred to a multisite intervention study completed the Pediatric Anxiety Rating Scale, Multidimensional Anxiety Scale for Children, Anxiety Disorders Interview Schedule, Child Behavior Checklist, and Revised Children's Anxiety and Depression Scale. Results suggest acceptable internal consistency of the Revised Children's Anxiety and Depression Scale. Modest convergent validity was found among the Revised Children's Anxiety and Depression Scale and other standardized measures of anxiety and depression. There were stronger correlations between Revised Children's Anxiety and Depression Scale Total scores and subscales of measures expected to correlate significantly than those not expected to correlate. One exception was a significant association between the Revised Children's Anxiety and Depression Scale and Child Behavior Checklist Attention subscale, calling into question the divergent validity in separating anxiety from attention problems. Overall, results suggest preliminary support for the Revised Children's Anxiety and Depression Scale in youth with high-functioning autism spectrum disorders.