Chronic depressions include major depressive disorder, recurrent, without full interepisode recovery; major depressive disorder, currently in a chronic (i.e., > or = 2 years) episode; double depression; dysthymic disorder; and those depressive disorders--not otherwise specified (NOS)--that are persistent or predictably recurrent with substantial disability. Strategic treatment decisions include (1) whether to treat with medication, psychotherapy, ECT, or other methods; (2) selection among specific agents with long-term efficacy and tolerability (preferably established by randomized controlled trials); (3) selection of the next treatment should the initial treatment fail or be found intolerable; and (4) deciding whether to provide maintenance treatment. Tactical decisions are those needed to optimally implement the strategies selected; for example, (1) how to optimally dose, (2) how long to continue an acute phase treatment trial, (3) how to measure outcome, and (4) how to identify and manage subsequent symptomatic breakthroughs or side effects (which may also require revisions in the initial strategies). Some antidepressant medications evidence efficacy and safety in acute phase treatment of the chronically depressed, but continuation and maintenance phase treatments for these patients are less well investigated and deserve further study. The clinical implications of what is known to date for managing these patients are discussed.