• Interviews with patients and two resource persons were used to determine primary psychiatric diagnoses in 577 consecutive men entering an alcohol treatment program (ATP) at a veterans hospital. Twelve months later, about 95% of the sample were successfully followed up with a patient and resource person Interview to establish the clinical course over the year for the four most populous diagnostic subgroups. At intake into the treatment program, the 432 group 1 primary alcoholic men were older, had a later age at onset of alcoholism, demonstrated a lower intensity of drinking, had fewer antisocial problems, and used fewer categories of drugs than the 60 men in group 2 with primary drug abuse and the 40 men in group 3 with primary antisocial personality disorder. During the follow-up, men in groups 2 and 3 had a greater likelihood of drug use, more police and social problems, and demonstrated higher (more adverse) outcomes on a clinical outcome scale. The nine group 4 men with primary affective disorder at intake demonstrated an increased risk for past suicide attempts and psychiatric care and had a higher rate of affective disorder in first-degree family members. These findings underscore the importance of distinguishing between symptoms (eg, sadness or antisocial problems) and diagnoses and the need to establish primary and secondary labels in substance abusers.