The fifteen essays written for this volume reflect the increasing importance for social scientists of ethnic, rather than physical or tribal, criteria for classifying modern population groups. The authors—from South Africa, the United States, South West Africa (Namibia), Nigeria, and Scotland—cover most of Africa south of the Sahara. They consider the range from large national population groupings to small-scale societies attempting to maintain their social boundaries, and discuss such topics as emergent nationalism, ethnic divisiveness, social distance, voluntary association, and the role of women. The first section is concerned with particular communities, peoples, and ethnic groups, and treats traditional tribal groupings as well as communities delineated on phenotypic grounds. In the second section, the focus turns to modern situations of interaction; the two major themes discussed here are situational ethnicity and situational realignment. The third section deals with color, one of the physical criteria of ethnic identification; here the authors discuss the political and legal implications of a system based on color. The last essay reports on current changes in attitude and organization within the countries of white-ruled southern Africa.