A comprehensive literature review compared the patterns of suicide and suicidal behavior for adolescents and adults to identify age-related similarities and differences. Particular attention was given to follow-up rates of suicide by psychiatrically treated persons in these age groups. The major findings were that (1) adults and adolescent suicide completers were similar with respect to their gender ratio, use of guns in the attempt, completion of the initial attempt, and serious psychopathology; (2) adolescents differed from adults in suicidal behavior in their greater attempt rate, higher attempt/completion ratio, and lower rates of short and intermediate completion following psychiatric treatment; (3) the suicide outcome following psychiatric hospitalization is eightfold greater in adults than in youths during the first 3.5 years postdischarge; and (4) the 5:1 male/female ratio is the same for both adolescent attempters who later suicide and for all U.S. 15-19-year-old suicide completers. The frequent practice of combining adult and adolescent suicide and suicide behavior findings can result in misleading conclusions.