Objective: To evaluate whether Attachment-Based Family Therapy (ABFT) is more effective than Enhanced Usual Care (EUC) for reducing suicidal ideation and depressive symptoms in adolescents. Method: This was a randomized controlled trial of suicidal adolescents between the ages of 12 and 17, identified in primary care and emergency departments. Of 341 adolescents screened, 66 (70% African American) entered the study for 3 months of treatment. Assessment occurred at baseline, 6 weeks, 12 weeks, and 24 weeks. ABFT consisted of individual and family meetings, and EUC consisted of a facilitated referral to other providers. All participants received weekly monitoring and access to a 24-hour crisis phone. Trajectory of change and clinical recovery were measured for suicidal ideation and depressive symptoms. Results: Using intent to treat, patients in ABFT demonstrated significantly greater rates of change on self-reported suicidal ideation at post-treatment evaluation, and benefits were maintained at follow-up, with a strong overall effect size (ES = 0.97). Between-group differences were similar on clinician ratings. Significantly more patients in ABFT met criteria for clinical recovery on suicidal ideation post-treatment (87%; 95% confidence interval [CI] = 74.6-99.6) than patients in EUC (51.7%; 95% CI = 32.4-54.32). Benefits were maintained at follow-up (ABFT, 70%; 95% CI = 52.6-87.4; EUC 34.6%; 95% CI = 15.6-54.2; odds ratio = 4.41). Patterns of depressive symptoms over time were similar, as were results for a subsample of adolescents with diagnosed depression. Retention in ABFT was higher than in EUC (mean = 9.7 versus 2.9). Conclusions: ABFT is more efficacious than EUC in reducing suicidal ideation and depressive symptoms in adolescents. Additional research is warranted to confirm treatment efficacy and to test the proposed mechanism of change (the Family Safety Net Study). Clinical Trial Registry Information: Preventing Youth Suicide in Primary Care: A Family Model, NCT00604097. (Contains 2 figures and 4 tables.)