Sanctuary cities in the USA, UK, and Canada aim to accommodate illegalized migrants and refugees in their communities. The concept of the “sanctuary city,” however, is highly ambiguous: it refers to a variety of different policies and practices, and focuses on variable populations in different national contexts. In this article, I examine the international literature to show how urban sanctuary policies and practices differ between national contexts and assess whether there are common features of sanctuary cities. I uncover legal, discursive, identity-formative, and scalar aspects of urban sanctuary policies and practices. These aspects assemble in ways that differ between countries. The article concludes by raising important practical and theoretical questions about urban sanctuary.