This fascinating study in the sociology of knowledge documents the refutation of scientific foundations for racism in Britain and the United States between the two World Wars, when racial differences were no longer attributed to cultural factors. Professor Barkan considers the social significance of this transformation, particularly its effect on race relations in the modern world. Discussing the work of the leading biologists and anthropologists who wrote between the wars, he argues that the impetus for the shift in ideologies came from the inclusion of outsiders (women, Jews, and leftists) who infused greater egalitarianism into scientific discourse. But even though the emerging view of race was constrained by a scientific language, he shows that modern theorists were as much influenced by social and political events as were their predecessors.