Despite being fundamental to democracy, the normative concept of the people, i.e. the demos, is highly unclear. This article clarifies the legitimacy of the demos’ boundaries by structuring the debate into three strains of justification: first, normative membership principles; second, its democratic functionality and the necessity of cohesion for this essential function; and third, a procedural understanding of the demos. It will be shown that normative principles can only justify its expansion towards the ideal of an unbounded demos. On the other hand, the democratic function of the demos can be understood as a criterion for its restriction. This, however, is only possible on the basis of an existing polity and not for the initial constitution of the demos. Consequently, a legitimate demos has to take both inclusionary and exclusionary tendencies into account. These tendencies need to be weighed against each other in the democratic process, which leads to a fundamentally procedural understanding of the legitimacy of the demos.