Race is one of the most elusive phenomena of social life. While we generally know it when we see it, it's not an easy concept to define. Social science literature has argued that race is a Western, socio-political concept that emerged with the birth of modern imperialism, whether in the sixteenth century (the Age of Discovery) or the eighteenth century (the Age of Enlightenment). The editors of this book point out that there is a disjuncture between the way race is conceptualized in the social science and medical literature: some of the modern sciences employ racial and ethnic categories, but they do so to analyze, diagnose, and treat particular conditions such as organ transplants for mixed-race children, heart disease, cancer, osteoporosis, skin disorders, obesity, and gastrointestinal diseases. As such, race has a physical, as opposed to a purely social, dimension. In order to more fully understand what we mean by "race", social scientists need to engage genetics, medicine, and health. To be sure, the long shadow of eugenics and the Nazi use of scientific racism have cast a pall over the effort to understand this complicated relationship between social science and race. But while the contributors of this volume reject pseudoscience and hierarchical ways of looking at race, they make the claim that it is time to reassess the Western-based, "social construction" paradigm. The chapters in this book consider three fundamental tensions in thinking about race: one between theories that see race as fixed or malleable; a second between the idea that race is a universal but modern Western concept and the idea that it has a deeper and more complicated cultural history; and a third between socio-political and biological/bio-medical concepts of race. Arguing that race is not merely socially constructed, the contributors, including Henry Louis Gates, Jr., Ann Morning, Jennifer Hochschild, Rogers Brubaker, Michael Keevak, Carolyn Rouse, and Sandra Soo-Jin Lee, offer a provocative collection of views on the way that social scientists must reconsider the idea of race in the age of genomics.