Patients with bulimia nervosa frequently have problems with alcoholism and other substance abuse. The goal of this study was to assess whether this relationship between eating abnormalities and substance abuse extends to subthreshold levels of dieting and substance use. A self-administered questionnaire assessing dieting and substance use (alcohol, cigarettes, and marijuana) was completed by 1,796 women prior to their freshman year in college. Using a scale derived from DSM-III-R criteria for bulimia nervosa and previous research in this population, subjects were categorized as nondieters, casual, intense, severe, at-risk or bulimic dieters. The relationship between the dieting-severity category and frequency and intensity of alcohol use and frequency of marijuana and cigarette use was assessed. DSM-III-R criteria for bulimia nervosa were met by 1.6% of the women. Only 13.8% of these women were nondieters. Increasing dieting severity was positively associated with increasing prevalence of alcohol, cigarette, and marijuana use and with increasing frequency and intensity of alcohol use. The bulimic and at-risk dieters were similar in their alcohol and drug use. The relationship between eating disorders and alcoholism and other substance abuse noted in clinical populations extends in a continuous, graded manner to subthreshold levels of dieting and substance use behaviors. Dieting-related attitudes and behaviors in young women may be related to increased susceptibility to alcohol and drug abuse.