In this depression prevention trial, 341 high-risk adolescents (mean age = 15.6 years, SD = 1.2) with elevated depressive symptoms were randomized to a brief group cognitive-behavioral (CB) intervention, group supportive-expressive intervention, bibliotherapy, or assessment-only control condition. CB participants showed significantly greater reductions in depressive symptoms than did supportive-expressive, bibliotherapy, and assessment-only participants at posttest, though only the difference compared with assessment controls was significant at 6-month follow-up. CB participants showed significantly greater improvements in social adjustment and reductions in substance use at posttest and 6-month follow-up than did participants in all 3 other conditions. Supportive-expressive and bibliotherapy participants showed greater reductions in depressive symptoms than did assessment-only controls at certain follow-up assessments but produced no effects for social adjustment and substance use. CB, supportive-expressive, and bibliotherapy participants showed a significantly lower risk for major depression onset over the 6-month follow-up than did assessment-only controls. The evidence that this brief CB intervention reduced risk for future depression onset and outperformed alternative interventions for certain ecologically important outcomes suggests that this intervention may have clinical utility. (Contains 2 figures and 2 tables.)