This article reviews the evidence on the adverse health consequences of low socioeconomic status, homelessness, and incarceration among drug users. Social and economic factors shape risk behavior and the health of drug users. They affect health indirectly by shaping individual drug-use behavior; they affect health directly by affecting the availability of resources, access to social welfare systems, marginalization, and compliance with medication. Minority groups experience a disproportionately high level of the social factors that adversely affect health, factors that contribute to disparities in health among drug users. Public health interventions aimed at improving the health of drug users must address the social factors that accompany and exacerbate the health consequences of illicit drug use.