This paper introduces the concept of “nation-state science” to describe the scientific work of ethnoracial classification that made possible the ideal of the homogenous nation-state. Swedish scientists implicitly defined their nation for Continental Europeans when they explicitly created knowledge about the “Lapps” (today's Sámi/Saami). Nation was coupled to state through such ethnoracial categories, the content of which were redefined as Sweden's geopolitical power rose and fell. These shifts sparked methodological innovations to redefine the Lapp, making it a durable category whose content was plastic enough to survive paradigm shifts in political and scientific thought. Idiosyncratic Swedish concerns thus became universalized through the scientific diffusion of empirical knowledge about Lapps and generalizable anthropometric techniques to distinguish among populations. What Sweden lost during the nineteenth century in terms of geopolitical power, it gained in terms of biopower: the knowledge and control of internal populations made possible by its widely adopted anthropometric innovations. Nation-state science helps unpack the interrelationships between state-building, nation-making, and scientific labor.