Early identification and treatment of social anxiety disorder (SAD) is critical to prevent development of a chronic course of symptoms, persistent functional impairment, and progressive psychiatric comorbidity. A small but growing literature supports the effectiveness of cognitive behavior therapy (CBT) for anxiety disorders, including SAD, in adolescence. The present randomized controlled trial evaluated the efficacy of group vs. individual CBT for adolescents with generalized SAD in relation to an educational/supportive psychotherapy that did not contain specific CBT elements. All three treatments were associated with significant reductions in symptoms and functional impairment, and in improved social skills. No differences between treatments emerged on measures of symptoms, but the CBT conditions demonstrated greater gains on behavioral measures. The implications of the findings are discussed.