BACKGROUND: Most clinical alcohol research is carried out on alcoholics who are in treatment, usually inpatients. However, most alcohol-dependent men and women never enter treatment, and even fewer ever receive inpatient care. Thus, some generally accepted data on the clinical course of alcoholism, derived from treatment samples, might not generalize to the entire population of alcohol-dependent individuals. This article characterizes the clinical characteristics of alcohol dependence in three groups of alcoholics, based on their histories of treatment for alcohol problems: those without prior rehabilitation; those with only outpatient approaches or Alcoholics Anonymous (AA); and subjects with an inpatient experience. METHODS: Semistructured interviews were administered to 3572 DSM-III-R-defined alcohol-dependent subjects from the Collaborative Study on the Genetics of Alcoholism. The clinical patterns were compared across the three groups of alcoholics: Group 1, never-treated (n = 1582; 44%); Group 2, histories of outpatient or AA only (n = 399; 11%); and Group 3, at least one inpatient experience (n = 1591; 45%). RESULTS: A progression was shown from Groups 1 to 3 for more general life problems (e.g., unemployment, marital instability); higher rates of additional drug dependencies and psychiatric disorders; and more alcohol-related adverse events. Logistic regression analyses revealed that those with no prior treatment were more likely to be women, Caucasian, and employed, and to report a lower rate of divorce/separation, lower levels of alcohol intake, and fewer alcohol problems. Among those who received help, inpatient care was predicted by an opposite profile. CONCLUSIONS: These results indicate that studies using data from inpatient populations may give a skewed picture of the clinical characteristics of alcohol dependence.