BACKGROUND: Anxietyisacommonandimpairingprobleminchildren andadolescentswith autism spectrumdisorder (ASD). There is emerg- ing evidence that cognitive-behavioral therapy (CBT) could reduce anx- iety in children with high-functioning ASD. OBJECTIVE: To systematically review the evidence of using CBT to treat anxiety in children and adolescents with ASD. Methods for this review were registered with PROSPERO (CRD42012002722). METHODS: We included randomized controlled trials published in En- glishinpeer-reviewedjournalscomparingCBTwithanother treatment, no treatment control, or waitlist control. Two authors independently screened 396 records obtained from database searches and hand searched relevant journals. Two authors independently extracted and reconciled all data used in analyses from study reports. RESULTS: Eight studies involving 469 participants (252 treatment, 217 comparison) met our inclusion criteria and were included in meta- analyses. Overall effect sizes for clinician- and parent-rated outcome measures of anxiety across all studies were d = 1.19 and d = 1.21, respectively. Five studies that included child self-report yielded an average d = 0.68 across self-reported anxiety. CONCLUSIONS: Parent ratings and clinician ratings of anxiety are sen- sitive to detecting treatment change with CBT for anxiety relative to waitlist and treatment-as-usual control conditions in children with high-functioning ASD. Clinical studies are needed to evaluate CBT for anxiety against attention control conditions in samples of children with ASD that are well characterized with regard to ASD diagnosis and co-occurring anxiety symptoms. Pediatrics 2013;132: e1341–e1350