In recent years, the U.S. federal government has aggressively sought to involve state and local government institutions more extensively and directly in the day-to-day regulation of immigration status and the interior enforcement of federal immigration laws. In this chapter, I discuss two sets of these initiatives - the efforts to involve state and local police in routine immigration enforcement and the development of federal issuance and eligibility standards for state driver's licenses - in order to explore the ways in which these developments may challenge conventional assumptions about the relationships between state and local governments and their non-U.S. citizen residents. Traditionally, U.S. immigration law has been understood to constrain state and local involvement in the regulation of immigration in part based on the premise that non-U.S. citizens are more likely to face hostility, discrimination, or disadvantage at the hands of state or local institutions than at the hands of the federal government. Certainly, it remains the case that non-U.S. citizens may often be vulnerable to hostility or discrimination by state and local government actors, as a number of recent examples make clear. However, as the federal government itself has become more aggressive in its regulation of immigration status, non-U.S. citizens are seeking and, in some instances, finding greater receptiveness for the protection of rights and liberties in state capitals and local city halls, rather than in Washington. In this context, the traditional assumptions concerning immigration, citizenship, and federalism may be incomplete.