It is not possible to police the movement of “aliens” without first determining who is and is not a citizen. Yet little scholarly attention has been devoted to the nature of citizenship determinations or their implication for our understanding of immigration enforcement as a whole. Thousands of U.S. citizens are caught up in immigration enforcement actions every year, and dozens of cases have come to light in which erroneous deportations can be traced to the lack of procedural protections within the deportation system, manifested in summary proceedings, lengthy detention, and lack of access to counsel. Such cases compel us to reconceptualize citizenship as not just a status that precedes immigration enforcement but also one that is, in a functional sense, produced by such enforcement. This insight has important consequences for both theoretical understandings of citizenship and constitutional analysis of immigration enforcement. Drawing on historical and contemporary material, this Article proposes a new understanding of “immigration exceptionalism,” exploring its implications for the rights of both citizens and noncitizens and highlighting its central reliance on the notion that citizenship status can function as a threshold jurisdictional inquiry. Arguing that such reliance is misplaced, this Article proposes a wholesale reconsideration of immigration enforcement’s procedural norms.