Screening for substance use and mental health problems among welfare recipients has increased in significance since 1996, largely because many studies have suggested that substance use problems may be linked to decreased employability and increased child abuse among those receiving welfare benefits. This article examines the unintended consequences and opportunities of screening public assistance recipients for use of intoxicating substances. Data from the Women's Employment Survey and the National Household Survey of Drug Abuse, both conducted in the late 1990s, were used to examine the prevalence and type of recent self-reported psychiatric disorders and drug use among welfare recipients. These data were used to assess the extent to which chemical testing of welfare recipients might identify those who need treatment for substance use problems. The authors argue that psychiatric disorders are more prevalent than drug use problems among Temporary Assistance for Needy Families (TANF) recipients. For this reason, screening for psychiatric disorders should be a higher priority than drug screening among members of this population. Therefore, the authors suggest that chemical testing be used only in conjunction with psychiatric screening so that resources are used more appropriately and the needs of welfare recipients are met in more sensitive ways.