Examined the relative importance of diagnostic and psychosocial factors in the prediction of adolescent suicidal ideation. Seventy-three high school students exhibiting emotional disturbance in the school setting completed a diagnostic interview and self-report measures assessing social support, family environment, negative life events, and problem solving. Using hierarchical regression analyses, only the presence of a pure internalizing disorder predicted suicidal ideation in addition to psychosocial variables. Interactions were found between psychiatric disorders and psychosocial variables. These results underscore the importance of including both diagnostic and psychosocial variables in research examining risk factors for adolescent suicidal behavior. Further, they suggest that adolescents presenting with psychiatric disorders, high levels of stress, and poor social support networks should be monitored for suicidality.