The author explains how the concepts of race and ethnicity became important in the US. He describes the history of current conceptions of race and its many meanings in biology and social life; the political aspects that gave it special meaning in the US, arguing that the popular conception of race is connected to the one-drop rule in the US; and its increasing importance in international law and politics. He discusses how sociologists have struggled with the use of race in ordinary language to structure social relations, how the concept of racism could facilitate better explanations, the sociological value of ordinary language conceptions of ethnicity, and possibilities for new research informed by a better understanding of philosophical issues. Annotation ©2016 Ringgold, Inc., Portland, OR (protoview.com)