Adolescent suicidality is a serious problem among American youth. Common risk factors for adolescent suicidality include depression and conduct problems but there is little agreement on the best means to assess these factors. We compared multiple informants (mothers, fathers, the adolescent and a sibling) and multiple assessment techniques using a sample of more than 460 families. Assessment techniques included paper-pencil instruments, observer ratings, and diagnostic interviews. Suicidality was assessed concurrently and two years after the risk assessment. Adolescent-reported paper-pencil instruments and diagnostic interviews were strongly associated with concurrent and future suicidality. Parents' report of adolescent feelings and behaviors were also useful. Observed behaviors were not useful in assessing suicidality risk factors. Clinical recommendations include utilizing paper-pencil and diagnostic adolescent risk factor assessment and focusing on emotions. (Contains 3 tables.)