In a sweeping work that traces the idea of race for more than three centuries, Audrey Smedley shows that race” is a cultural invention that began to appear around the turn of the eighteenth century. In its origin, race was not a product of science but a folk ideology reflecting a new form of social stratification and a rationalization for inequality among the peoples of North America. This third edition incorporates recently published new source materials on the history of race ideology. Because race” now has global manifestations, it also introduces the work of scholars who are examining the spread of race ideology cross-culturally. The new edition of Race in North America also looks more closely at the positions and arguments of contemporary race scientists. Although objective scientists have shown that any two humans are 99.9% alike genetically, race scientists maintain that the remaining difference of one-tenth of one percent is highly significant, accounting for many biological and behavioral differences that they assume to be hereditary. Race scientists contend, for example, that there are race differences in diseases and responses to medications, along with differences in intellect and in talent and ability in such fields as sports. Thus, they claim, race is a valid biological concept. Smedley argues that no amount of research into biological or genetic differences can help us understand the phenomenon of race in American society. Race can only be understood as a component of the sociocultural domain, not the domain of biology.