This article draws upon recent research on race and diversity, much of it conducted by the author and his collaborators on the American Mosaic Project at the University of Minnesota, to provide a critical-theoretical perspective on multiculturalism in contemporary American culture. It is based upon three main empirical findings. The first is that Americans are, on initial inspection, generally quite open to and optimistic about diversity. Further analysis and deeper probing, however, reveals a second, cross-cutting discovery: that thought and talk about diversity is marked by a series of underlying tensions and misgivings. The third and perhaps most important finding is that the discourse about diversity is deeply informed and determined-over-determined perhaps-by race in the United States. Taken together, it is argued that the contradictory, race-based attitudes Americans exhibit toward diversity reflect and reproduce many of the key, animating ambivalences of multiculturalism in both theory and practice: for example, the tensions between individuals and groups and between abstract ideals and empirical realities. The article concludes by suggesting that multiculturalism is not only at a crossroads in the United States but is a crossroads where many conflicting impulses and ideals about solidarity, belonging, and equality come together in the same cultural space.