For decades data have been collected comparing health care in racial and ethnic groups. The use of such groups in health services research assumes that standard, reliable, and valid definitions of race and ethnicity exist and that these definitions are used consistently. In fact, race is a term often used, but ill defined. It can incorporate biological, social, and cultural characteristics of patients and can refer to both genetic and behavioral traits. Various investigators have reported differences between racial and ethnic groups in health status, disease manifestation and outcome, resource utilization, and health care access, often specifying neither a definition of race nor the measurement they used to classify their study populations. The role of race as an explanatory variable in health services research requires greater scrutiny than many researchers currently provide. Many studies use race as a proxy for other socioeconomic factors not collected in the research effort. This article explores the ambiguities about race as an explanatory variable that render such research difficult to interpret. We suggest that health services researchers focus on nonracial socioeconomic characteristics that might be both more informative and more useful in guiding policy formation.