Chronic forms of depression account for approximately one third of all depressions. They are underrecognized and undertreated. This article defines the types of chronic depressions (dysthymic disorder, double depression, chronic major depression, and major depression in incomplete remission). A review of treatments for patients with these conditions is provided. The basic principles of treatment of chronic depression involve longer treatment and higher doses than are usually required for acute major depression. The impact of psychosocial disability and severity of depressive symptoms can be ameliorated with appropriate treatment. Newer treatments, such as the combination of psychotherapy and pharmacotherapy, may prove to be of greatest benefit for individuals with chronic mood disorders.