This study examines the prospective relationship between insomnia symptoms and suicide attempts in high-risk youth. We obtained depressive symptoms, insomnia symptoms, and suicide ideation measures from clinical records of 206 adolescents ages 12-17 at entry and discharge from a suicide prevention intensive outpatient program. Information about whether the participant made a suicide attempt was available through six months after discharge. Patients were mainly girls (79.1%; n = 163) with depression (89.8%; n = 185). Associations between insomnia symptoms, attempts within 6 months of discharge, persistent insomnia symptoms, and suicide ideation at discharge were tested with multiple regression analyses. Entry insomnia symptoms were prospectively associated with attempts when controlling for age, sex, and previous attempts, but insomnia symptoms at discharge were not. Suicide ideation at discharge was associated both with entry insomnia symptoms and attempts within 6 months of discharge. When entry and discharge suicide ideation were controlled, the association between entry insomnia symptoms and attempts lost significance. However, the association between discharge ideation and attempts remained significant. Insomnia symptoms contribute indirectly to suicide attempt risk after discharge. Intensive treatment for ideation and reducing insomnia symptoms could reduce discharge suicide risk and subsequent suicide attempts.