Our objective was to analyze differences in clinical characteristics and comorbidity between different types of adolescent depressive disorders. A sample of 218 consecutive adolescent (ages 13-19 years) psychiatric outpatients with depressive disorders was interviewed for DSM-IV Axis I and Axis II diagnoses. We obtained data by interviewing the adolescents themselves and collecting additional background information from the clinical records. Lifetime age of onset for depression, current episode duration, frequency of suicidal behavior, psychosocial impairment, and the number of current comorbid psychiatric disorders varied between adolescent depressive disorder categories. The type of co-occurring disorder was mainly consistent across depressive disorders. Minor depression and dysthymia (DY) presented as milder depressions, whereas bipolar depression (BPD) and double depression [DD; i.e., DY with superimposed major depressive disorder (MDD)] appeared as especially severe conditions. Only earlier lifetime onset distinguished recurrent MDD from first-episode MDD, and newly emergent MDD appeared to be as impairing as recurrent MDD. Adolescent depressive disorder categories differ in many clinically relevant aspects, with most differences reflecting a continuum of depression severity. Identification of bipolarity and the subgroup with DD seems especially warranted. First episode MDD should be considered as severe a disorder as recurring MDD.