The authors systematically evaluated a selected population of juvenile offenders for the prevalence of affective disorders. Seventy-one (40 male, 31 female) serious juvenile offenders were interviewed using the Schedule for Affective Disorders and Schizophrenia (SADS). They were then diagnosed using the Research Diagnostic Criteria (RDC) and the DSM-III. The Hamilton Rating Scales (HRS), Carroll Self-Rating Scale (CSRS), and Global Rating Scale for Depression (GRS) were also obtained for each subject. Eleven (15%) subjects were diagnosed as having an active major depressive disorder (MDDa), 6 (8%) subjects were diagnosed as having a major depressive disorder in remission (MDDr), and 9 (13%) as having a minor depressive disorder (mDD). The HRS, CSRS, and GRS differentiated the MDDa from the other three groups including MDDr, mDD and all other psychiatric diagnoses. RDC subtypes of depressive disorders were identified in those juvenile offenders with active major depressive disorders (MDDa) and compared to a population of hospitalized adolescents with major depressive disorders. There were significant differences in the distribution of the subtypes identified. Secondary, agitated and endogenous subtypes occurred significantly more often. The diagnostic, prognostic and therapeutic significance of these findings are discussed.