This study contrasts the prevalence of alcohol-related symptoms, ages of onset of alcoholism milestones, and lifetime prevalence of other psychiatric disorders in three samples of alcohol-dependent individuals: alcoholics sampled from a variety of clinical settings (not necessarily alcoholism treatment facilities), relatives of alcoholic probands who participated in a Family Study of alcoholism, and alcoholics identified in the St. Louis Epidemiologic Catchment Area survey. Alcohol dependence (with or without abuse) was assessed using DSM-III diagnostic criteria for all samples. Clinical alcoholics had significantly more lifetime alcohol symptoms than Family Study and Community alcoholics and a significant excess of many alcohol symptoms. Onset information indicated that the three groups were similar in terms of appearance of milestones of alcohol dependence. For females aged 45 or younger, lifetime prevalence of major depression was high in both Clinical and Family Study alcoholics compared with Community alcoholics; male alcoholics from the Community Study had an excess of drug dependence. Findings suggest that, although alcoholics identified in clinical settings may have more severe alcohol dependence, certain types of psychiatric comorbidity are present to a greater degree in other samples of untreated alcoholics.