Chronic depression, which is marked by a course of illness lasting 2 years or more, encompasses 4 subtypes of depressive illness: (1) chronic major depressive disorder, (2) dysthymic disorder, (3) dysthymic disorder with major depressive disorder ("double depression"), and (4) major depressive disorder with poor interepisodic recovery (i.e., in incomplete remission). In the 1990s, chronic depression had a reported prevalence rate of 3% to 5% and accounted for 30% to 35% of all cases of depression in the United States. The authors present an algorithm modified from the Texas Medication Algorithm Project for patients with chronic depression. This treatment algorithm recommends a progression of steps or stages in treating chronic depression. The first stage is monotherapy with the selective serotonin reuptake inhibitors, nefazodone, bupropion sustained release, venlafaxine extended release, mirtazapine, or psychotherapy. Later options include combination therapy, electroconvulsive therapy, atypical antipsychotics, and novel treatments. Utilization of a comprehensive treatment algorithm for chronic major depression should encourage efficient, efficacious treatment.