OBJECTIVE: This article reviews the literature on racial, ethnic, and socioeconomic disparities in morbidity and mortality, focusing on substance use and abuse. OBSERVATIONS: In most populations and societies, people of higher social position live longer and remain healthier than those of lower position. Disparities in morbidity and mortality across ethnic groups also exist. Mortality rates for African Americans are about 1.6 times higher than those for white, with much higher disparities for certain causes, such as HIV/AIDS and diabetes. Disparities also exist in the level of substance use and abuse. CONCLUSION: Racial and ethnic differences in health and health behaviors, including substance use and abuse, may partly reflect biological differences, but it is more likely that they can be explained largely by socioeconomic differences, cultural factors, and prejudice and discrimination, both institutional and individual.