Ethnicity is a salient feature of numerous societies throughout the world. Few societies are ethnically homogeneous, even when they proclaim themselves to be. Consequently, ethnicity has been a preoccupation of sociologists since the early days of the discipline (although more so in the United States than elsewhere).

Yet there is not complete agreement on how the subject should be defined. In the past, it was common to highlight cultural difference as an essential feature of ethnic distinctiveness (see, e.g., van den Berghe 1967). Recently, this has lost favor on the grounds that cultural differences may vary from one setting to another and from one historical period to another. Following an approach attributed to Frederik Barth (1969), recent definitions have therefore focused on the existence of a recognized social boundary. But still among the most useful definitions is the classic one of Max Weber ([1922] 1968): An ethnic group is one whose...