Background Rates of suicidal ideation and behaviours as well as associated risk factors are examined among youth recruited from five public sectors of care (i.e. child welfare, juvenile justice, special education services, alcohol and drug services, and county mental health). Method 1057 youth (ages 11–18) completed a diagnostic interview and questionnaires assessing relevant suicide risk factors at baseline and 2-year follow-up. Results While past year thoughts about death (28%) and talking about killing oneself (7.1%) were comparable to community norms, rates of lifetime suicide attempts (20.1%) were considerably higher in this sample. However, youth in the special education sector reported significantly more suicidal thoughts and behaviours relative to the other sectors. In multivariate analyses, longitudinal predictors of suicidality included major depression, female gender, and involvement in the special education sector. Conclusions Efforts to implement screening and evidence based interventions for depression and suicide in the public sector, particularly special education services, are necessary.