It was found that most past-month drug users were not participants in AFDC, Medicaid, or Food Stamps. Overall, 5.4 percent, 8.9 percent, and 9.9 percent of past-month drug users participated in AFDC, Medicaid, and Food Stamps, respectively. Prevalence rates of self-reported nonmedical drug use were somewhat higher among program participants than in the general population. In 1991, past-month drug use for persons 15 years of age and older was 10.5 percent for AFDC households, 9.4 percent for Medicaid households, and 10.1 percent for Food Stamp households. Three or more episodes of binge drinking in the past month were reported by 8.2 percent of women in AFDC households and by 3.8 percent of all women aged 15 years and older. Among men and women combined, heavy episodic drinking was reported by 8.6 percent of all persons aged 15 years and older and by 8.7 percent of those in AFDC households. Marijuana was the most frequently reported illicit drug use by persons aged 15 years and older. Although the proportion of persons reporting cocaine use was small, rates among persons 15 years of age and older were higher among those in households receiving AFDC, Medicaid, or Food Stamps than in the general population. In all program participant groups, drug use tended to be concentrated among younger persons. Persons who reported drug use were much less likely to be married, many who reported past-month drug use were unemployed, and illicit drug use was not concentrated in large cities. Among persons who lived in AFDC and Medicaid households and who reported past-month drug use, a larger proportion were below the poverty level than among all AFDC and Medicaid participants. Among Food Stamp participants, however, a small proportion of past-month drug users were below the poverty level. Study findings suggest that program administrators should recognize the presence of persons with substance abuse problems in their caseloads in order to improve the ability to serve these individuals and to better focus prevention and treatment efforts. 3 references, 5 footnotes, and 23 tables