I discuss the Puerto Rico case in comparative perspective, placing it within the contours of the issues and debates that usually frame the contemporary discussion of sub-state demoi and multinational democracies. I first analyze the constitutional structures that frame Puerto Rico´s political status, as a territory that was acquired as a colony by the United States, but that has undergone some limited constitutional evolution in the last 100 years. Second, I characterize the nature of the territorial regime that exists in Puerto Rico, especially since 1952, drawing on the literature on comparative federalism and comparative constitutional law. Third, I then focus on a key component of the mixture of subordinated autonomism and colonial constitutionalism that characterizes Puerto Rico’s political status: the inferior, differentiated U.S. citizenship of the residents of Puerto Rico, for which I use the term “asymmetric territorial citizenship.” Fourth, I historicize this second-class citizenship and show how it is a marker of empire, drawing on the history of the British, French, Spanish, and U.S. empires. Fifth, I discuss how subordinated autonomism and colonial constitutionalism structure political developments in Puerto Rico, in view of its nature as a sub-state demos, and explain how and why its internal political tendencies and its political party system have evolved.