This study investigates the impact of suicidality on treatment outcome in 107 depressed adolescents who participated in a clinical trial, and received either cognitive-behavioral (CBT), systemic-behavioral-family (SBFT), or non-directive-supportive therapy (NST). Suicidal depressed adolescents had a higher dropout rate and were more likely to be depressed at the end of treatment, in large part due to the particularly poor response of suicidal patients to NST. The relationship between suicidality and treatment response was mediated by severity of depression and hopelessness at intake. Hopelessness should be specifically targeted early in treatment. Suicidal depressed adolescents should not receive NST but a specific treatment like CBT.