Anxiety disorders are commonly comorbid in adolescents and young adults with high-functioning autism. Cognitive-behavioral treatments (CBT) for anxiety, when adapted and expanded to target autism spectrum disorder (ASD) characteristics, may be beneficial, but there is minimal evidence to guide clinicians in their application. This multiple-baseline design study evaluated the initial efficacy of a CBT protocol adapted to address anxiety symptoms and adaptive functioning in this population. Anxiety and ASD symptoms were assessed for six participants at intake, after baseline, posttreatment, and at 1-month follow-up. Parent-and child-reported anxiety was also assessed during baseline and treatment. Visual inspection and reliable change index scores were used to evaluate change. All participants improved on clinician-rated measures of disorder severity, and gains were maintained at follow-up. Results were more equivocal for parent-and self-rated anxiety and parent-rated ASD, partly because of spontaneous changes during baseline.