The authors evaluate the clinical and research significance of the diagnosis of secondary depression by comparing 48 cases of primary and 26 cases of secondary depression. The patients with secondary depression have a higher familial prevalence of alcoholism, affective disorder, and drug abuse. The groups differ somewhat on a few sociodemographic, behavioral, and attitudinal variables but are similar in symptomatology, sex ratio, onset and duration of symptoms, treatment received, and response to treatment. These results suggest that the distinction between primary and secondary depression should be retained in research that examines neurochemistry or genetics. Primary and secondary depression appear to be identical from the persepctive of clinical care. Management of these patients should emphasize the diagnosis of depression rather than antecedent diagnoses.