This article draws on comparative evidence from four American and European cities – San Francisco, Houston, Barcelona, and Milan – to develop a framework for explaining variation in the types of sanctuary policies that city officials have adopted to protect and integrate undocumented immigrants into aspects of city life. While prior scholarship has focused on explaining whether cities adopt sanctuary policies at all, this article instead explains whether adopted policies bring symbolic or substantive benefits to undocumented immigrants and whether adopted policies conform to or confront the goals of national immigration policies. To explain the observed variation in adopted sanctuary policies across these four Global North cities, this article combines existing theoretical approaches to local immigration policymaking that emphasise the relevance of either city-specific contextual factors or the supra-local context in which different cities are embedded.