Suicide rates of young people are increasing in many geographic areas. There is a need to recognize more precisely the role of specific mental disorders and their comparative importance for understanding suicide and its prevention. The authors reviewed the published English-language research, where psychiatric diagnoses that met diagnostic criteria were reported, to reexamine the presence and distribution of mental disorders in cases of completed suicide among young people worldwide. The number and geographical distribution of cases were limited (N = 894 cases). The majority of cases (88.6%) had a diagnosis of at least 1 mental disorder. Mood disorders were most frequent (42.1%), followed by substance-related disorders (40.8%) and disruptive behavior disorders (20.8%). Those strategies focusing exclusively on the prevention and treatment of depression in young people need to be reconsidered. A comprehensive suicide prevention strategy among young people should target mental disorders as a whole, not depression alone, and consider contextual factors.