The term “sanctuary” has long expressed a sympathy for immigrants’ rights and resistance to federal immigration enforcement. Recently, the word has become associated with another divisive political topic, as local governments have begun declaring themselves “Second Amendment Sanctuaries” in defiance of statewide gun-control measures they deem unconstitutional. This gun-rights resistance movement not only flips the political script on the nature of sanctuaries, but also presents important and challenging questions about local–state power sharing, the proper scope of “subfederal commandeering,” and the role of coordinate branches in constitutional decision-making. This Article provides the first scholarly treatment of Second Amendment Sanctuaries. In doing so, it explores both the unique facets of this new localism and the broader implications for sanctuary movements generally. Most early commentary dismisses Second Amendment Sanctuaries as purely symbolic and presumptively invalid pursuant to state preemption principles and the judicial supremacy model of constitutional interpretation. This Article challenges that narrative and articulates a theory of limited viability for Second Amendment Sanctuaries and other local intrastate resistance movements more broadly. The theory this Article presents proceeds in three parts, with each part presenting a novel approach to local–state governmental conflict that contributes to the existing literature. First, localities can resist broad state preemption in limited circumstances via the state’s “home rule” provisions when local regulation of a particular issue is rooted in history and has normative policy appeal. Second, localities may passively resist statewide regulation through a form of “subfederal anticommandeering” analogous to the Tenth Amendment’s anticommandeering principles protecting states from federal overreach, so long as the locality takes no affirmative steps to frustrate state enforcement. Third, local enforcement officers may defend their resistance on substantive constitutional grounds when the right at issue is not firmly settled by the judiciary. This “first impression departmentalism” reflects the belief that all coordinate branches of government should play a role in defining the contours of constitutional provisions when emerging doctrine remains in a state of flux. These three principles counsel in favor of the viability of at least some Second Amendment Sanctuaries as currently constructed, as well as possible future “gun control sanctuaries” resisting statewide firearm deregulation.