This volume is designed first to provide a theoretical orientation and historical perspective on the rise of the middle classes in modern civilization, and second, to portray the social and political roles these classes have played and continue to play in the United States over the past century, with particular reference to the American class structure and political economy. Our method is necessarily both historical and sociological and offers an orientation for understanding contemporary American society. The essays included here were written between 1926 and 1982: they reveal both the genealogical development of sociological thought about the middle classes and the substantive content of these classes'' life styles, status claims and political orientations. The present work stresses empirical studies and puts forth neither a theoretical interpretation nor a conceptual taxonomy; rather it delineates the emergence and the social and political significance of the new middle classes in relation to the classes, above and below, that preceded them.