There is a lively ongoing debate among philosophers and social scientists about the reality of race and among social scientists about the reality of caste and ethnicity. This paper tries to sort out what the issues are and makes some preliminary suggestions about what the evidence shows. Standard philosophical analyses try to find the necessary and sufficient conditions of our concept of race. I argue that this is not the best way to approach the issue and that the reality of (...) these concepts should be taken as a scientific realism question; that is, do our best social scientific accounts of these phenomena show that appealing to the concepts of race, caste, and ethnicity is essential to successful social science explanation? I argue that in some cases that is the case and lay out the empirical issues involved. (shrink)