The authors review the history of the concept of dysthymia and the literature on the epidemiology, course, and treatment of chronic depression. They present a critical discussion of DSM-III and DSM-III-R criteria for dysthymic disorder. On the basis of this review, they suggest that future revisions of the nomenclature include further subcategorization of chronic depressive disorders and that the term "dysthymic disorder" be reserved for chronic depressive disorders with an insidious onset at an early age. The relationships between dysthymic disorders and personality disorders and the response of subcategories of chronic depression to different treatment modalities need to be researched.