Context: Adolescent depression is highly prevalent and has substantial morbidity, including suicide attempts, school dropout, and substance abuse, but many depressed adolescents are untreated. The school-based health clinic offers the potential for accessible and efficient treatment, although it is unknown whether school-based clinicians can be trained to implement evidence-based psychotherapies for depression in routine care., Objective: To assess the effectiveness of interpersonal psychotherapy modified for depressed adolescents (IPT-A) compared with treatment as usual (TAU) in school-based mental health clinics., Design: A 16-week randomized clinical trial was conducted from April 1, 1999, through July 31, 2002., Setting: Five school-based mental health clinics in New York City, NY. Patients Sixty-three adolescents referred for a mental health intake visit who met eligibility criteria. Eligible patients had a mean Hamilton Depression Rating Scale score of 18.6 (SD, 5.5) and a mean Children's Global Assessment Scale score of 52.6 (SD, 5.5) and met DSM-IV criteria for major depressive disorder, dysthymia, depression disorder not otherwise specified, or adjustment disorder with depressed mood. Mean age was 15.1 years (SD, 1.9 years). The sample was predominantly female (n = 53 [84%]), Hispanic (n = 45 [71%]), and of low socioeconomic status. Intervention Patients were randomly assigned to receive IPT-A (n = 34) or TAU (n = 29) from school-based health clinic clinicians., Main Outcome Measures: The Hamilton Depression Rating Scale, Beck Depression Inventory, Children's Global Assessment Scale, Clinical Global Impressions scale, and the Social Adjustment Scale-Self-Report., Results: Adolescents treated with IPT-A compared with TAU showed greater symptom reduction and improvement in overall functioning. Analysis of covariance showed that compared with the TAU group, the IPT-A group showed significantly fewer clinician-reported depression symptoms on the Hamilton Depression Rating Scale (P =.04), significantly better functioning on the Children's Global Assessment Scale (P =.04), significantly better overall social functioning on the Social Adjustment Scale-Self-Report (P =.01), significantly greater clinical improvement (P =.03), and significantly greater decrease in clinical severity (P =.03) on the Clinical Global Impressions scale., Conclusions: Interpersonal psychotherapy delivered in school-based health clinics is an effective therapy for adolescent depression. This effort is a significant step toward closing the gap between treatment conducted in the laboratory and community clinic.