This article offers a preliminary sketch of a multidimensional model of variable constitutional authority rooted in principles and practices of popular sovereignty. To do so, it draws on three sets of criteria on which James Madison relied in The Federalist: those based on processes of popular authorization, principles of republican governance, and commitments to securing rights. These criteria support analysis of gradations of constitutional authority, not only claims that it has been present or absent. Taking into account ways that the Constitution partially rather than fully represented "the people" enables a richer, more nuanced treatment of the Constitution's initial authority than more categorical approaches such as traditional models of originalism. This approach underscores in particular the importance of being attentive to ways that the Constitution's initial authority and meaning were pluralistic, contested, and of qualified reach, instead of being fully and definitively established at the time of the founding.