Enumeration, even the contemporary census, cannot be characterized as neutral and objective data collection; official categories both shape and are shaped by national cultures. This article examines the forms, laws, and procedures of Japanese household registration (koseki) and national censuses in three cases from the modern period (1868 to post-World War II). Each case isolates a particular time period to show how broad political cultures, such as Westernization, the development of state welfare, and democratization, were codified or reflected discursively in enumerative programs. In each case, categories shifted the substantive and practical meanings of individuals in families and of household heads in relation to the state. In the early Meiji period (1868-1912), an aristocratic, head-centric social order was imposed on all classes through household registration. By the late Meiji and through the Taisho (1912-36) and early Showa periods (1936-89), census categories reflected a new household model based on economic and spatial relations. In the reconstruction period following World War II, the household register embodied the dramatic changes to the civil code that established equality of sexes and the nuclear family as the fundamental social unit. By the 1960s, however, census forms reflected a return of national cultural discourse to hierarchical, extended-stem family households.