This study examines the ways that states have attempted to pigeon-hole the people within their boundaries into racial, ethnic, and language categories. These attempts, whether through American efforts to divide the U.S. population into mutually exclusive racial categories, or through the Soviet system of inscribing nationality categories on internal passports, have important implications not only for people's own identities and life chances, but for national political and social processes as well. The book reviews the history of these categorizing efforts by the state, offers a theoretical context for examining them, and illustrates the case with studies from a range of countries.