Depression is a common but highly treatable mood disorder. Unfortunately, two thirds of depressed patients may never receive appropriate intervention. Because of individual and societal barriers to the diagnosis, depressive symptoms often go unrecognized. However, primary care physicians are in a unique position to surmount these obstacles by being alert to manifestations of the disorder. Treatment with antidepressant drugs, psychotherapy, electroconvulsive therapy, or a combination of these is very efficacious. The choice of method is based on such factors as history of previous response, severity of disease, concomitant medical illness, and patient preference.