To travel undetected by state authorities and criminal predators, Central Americans pass as Mexican during their journey to the United States. This ‘passing’ underscores the ambiguities of social roles, such as nationality. Over time, these performances partially reconstruct imagined communities, blurring the boundaries between foreigners and citizens. However, international-relations scholarship tends to overlook how uncoordinated everyday practice complicates borders in a globalized world. By tracing the co-constitutive relationship between migration policing, national performances, and transnational routes, this article reveals the makeshift nature of the identities that underscore distinctions between citizens and foreigners. I argue for the continued inclusion of ethnography as a method for exploring the dynamic relationship between territory, state, and nation. Migrants complicate borders, but also suffer the very real, material consequences of both state and nonstate violence. My analysis of clandestine transnationalism therefore chronicles challenges to, and reconfigurations of, sovereignty.