Nationalism and populism are frequently confused in popular and academic discourse alike. The aim of this article is to shed some light on the mutual entanglement of nationalism and populism by delineating the historical and structural conditions out of which the two discourses arise. Specifically, I demonstrate that nationalism and populism are symptomatic of the coupling of two political principles within the territorial frame of the modern state: the principle of political representation and the principle of popular sovereignty. As a result, the functioning of modern politics requires a double move: the identification of who the sovereign people are and the re-presentation of the people in the place of power. I argue that nationalism corresponds to the first of these moves while populism corresponds to the second. Nationalism and populism are therefore intrinsically intertwined: even if they may be conceptually distinguished, they cannot be fully separated. This also suggests that nationalism and populism are much more pervasive in modern political theory and practice than has generally been recognised. The extreme phenomena to which the terms commonly refer are just especially intense and polarised manifestations of two underlying logics that are always-already at work.