The causes of racial and ethnic inequalities in health and the most appropriate categories to use to address health inequality have been the subject of heated debate in recent years. At the same time, genetic explanations for racial disparities have figured prominently in the scientific and popular press since the announcement of the sequencing of the human genome. To understand how such explanations assumed prominence, this essay analyzes the circulation of ideas about race and genetics and the rhetorical strategies used by authors of key texts to shape the debate. The authority of genetic accounts for racial and ethnic difference in disease, the author argues, is rooted in a broad cultural faith in the promise of genetics to solve problems of human disease and the inner truth of human beings that is intertwined with historical meanings attached to race. Such accounts are problematic for a variety of reasons. Importantly, they produce, reify, and naturalize notions of racial difference, provide a scientific rationale for racially targeted medical care, and distract attention from research that probes the complex ways in which political, economic, social, and biological factors, especially those of inequality and racism, cause health disparities.