The legal rights of a person within a state depend in part on their migration status. Many states across the world deny non-citizen residents or ‘denizens’ certain political, socio-economic, and cultural rights granted to every citizen alike. This book tackles pressing moral questions raised by legal rights-differentiation by citizenship status by drawing on the ethics of migration, citizenship, multiculturalism, refuge as well as on normative theories of law, territory, and settler colonialism. Egalitarian values, at the heart of liberal democracy, ground a presumption against legal rights-differentiation. Any deviation from legal equality stands in need of justification. What, if anything, could justify legal rights-differentiations along the lines of citizenship? When, if ever, is it morally permissible for states to deny denizens certain legal rights granted to every citizen alike? This book scrutinizes these politically increasingly salient questions from a wide range of perspectives and drawing on recent literature. This book will be of great interest to philosophers, legal and political theorists, and researchers studying migration studies, philosophy, human rights, law and politics. This book was originally published as a special issue of Critical Review of International Social and Political Philosophy.