This report is based upon a long-term study from the Washington University Psychiatry Clinic. The study began with a systematic clinical evaluation of 500 patients, which was followed by a "blind" study of first-degree relatives and a "blind" follow-up of the index subjects. The present report deals with the diagnosis of alcoholism at index, at follow-up, and among the first-degree relatives. The results indicate that the criteria used for the diagnosis of alcoholism select patients who show a satisfactory degree of diagnostic consistency over many years. Furthermore, the diagnostic criteria select cases associated with a significant increase in the familial risk of alcoholism. Alcoholism was the only psychiatric disorder found to be increased among first-degree relatives of alcoholic probands. On the other hand, alcoholism in the probands was found to be associated with secondary depression, secondary mania, antisocial personality, Briquet's Syndrome, and drug dependence. None of these disorders, however, was found at an increased prevalence among the first-degree relatives of the alcoholics, suggesting that these associated disorders may play a significant role in the seeking of psychiatric care by patients with alcoholism.