Background: Social anxiety disorder (SAD) in children is highly prevalent but current treatments are not effective for all patients. Aim: A group treatment based on empirically driven etiological models including psychoeducation, cognitive restructuring, exposure, and social skills training was examined. Method: The study examined treatment success using a SAD-specific cognitive behavior group therapy in a randomized controlled trial ( N = 74, 8 – 12 years, blind randomized allocation to treatment [CBT; n = 42] and waitlist [WLC; n = 32]). Results: Compared to WLC, parents of children in the CBT group reported a decrease in symptoms (CBT: d = 1.02, WLC: d = 0.06), while children did not differ in two measures of social anxiety. An estimate of total treatment effects showed a steady decrease in social anxiety symptoms (child report pre- to posttreatment: d = 0.50 – 0.52, posttreatment to follow-up: d = 0.37 – 0.39; parent report pre- to posttreatment: d = 0.92, posttreatment to follow-up: d = 0.69). Conclusion: While group treatment is most likely an effective approach, parents reported stronger social anxiety symptom reduction than children. The selection of measures for the assessment of SAD and treatment success and further modifications of exposure-based approaches are to be considered in future research.