States have enacted a wave of statutes over the past several years preempting local government law and policies that potentially promote public health in various ways. Among these local preemption measures are statutes in at least 9 states that outlaw municipal policies providing some form of "sanctuary" to immigrants. Such policies, and their preemption, have importance both for direct access to health services and for broader social determinants of health.This article gauges the coverage and potential impact of these state preemption laws based on key informant interviews nationally and a close legal analysis of relevant laws and policy documents. It distinguishes between preemption laws focused on law enforcement cooperation and those that also encompass a wider array of "welcoming" policies and initiatives. It also distinguishes between more passive forms of preemption that prohibit barring cooperation with federal immigration enforcement, and those statutes that more affirmatively require active measures to assist federal enforcement.Drawing these distinctions can help municipalities determine which immigrant-supportive measures are still permitted, and how best to mitigate the adverse public health effects of these preemption laws.