There are continuing difficulties within social science surrounding concepts of race. This book suggests that these difficulties stem from the uncertain ontological and epistemological status of ideas about race, itself a consequence of the recognition that concepts of race have all but lost their relevance as sociologically significant descriptions. This book surveys ways in which social scientists have attempted to come to terms with this situation, before developing an alternative approach based on recent work by realist authors. This approach offers a radical revision of orthodox debates about race concepts, about the possibility of a social science and about the nature of empirical research. This illustrated through two policy examples: an account of post war migration to the UK, and debates about trans-racial adoption in the UK and the USA.