This study investigates the relation of ego development, age, gender, and diagnosis to suicidality among 219 adolescent psychiatric inpatients. Using the Diagnostic Interview Schedule for Children, adolescents were classified as suicide attempters or as nonsuicidal and were categorized into three diagnostic groups: affective disorder, conduct disorder, or mixed conduct-affective disorder. Ego development measurement was used to assess developmental maturity. Chi-square analyses demonstrated a relation between suicide attempts and developmental complexity. Attempters were more likely to be diagnosed with affective or mixed conduct-affective disorders and to be girls. Suicidality was not associated with age in this sample. Log-linear analyses demonstrated the interplay of known suicide risk factors with the important new dimension of developmental level.