There has been a dramatic increase in attention to comorbidity between psychiatric disorders and substance abuse in both clinical and research settings. Patients with major psychiatric conditions and substance abuse often fall between the cracks in clinical settings because of administrative distinctions between substance abuse and mental health. This article reviews the evidence regarding an association between alcoholism and depression in clinical and epidemiologic studies. Longitudinal and family-genetic studies are also reviewed to address possible mechanisms for the association between alcoholism and depression.