Public political debate about migration has become increasingly important and increasingly heated; substantive engagement with the morality of migration, however, is more uncommon. This book defends a moderate account of the right to exclude, on which the state may exclude some unwanted would-be migrants—but on which there are significant constraints on how and when that right can be exercised. The book grounds this in a particular vision of how exclusion might be justified, on which states are possessed of a presumptive right to avoid unwanted forms of political relationship. This account of the right to exclude is then applied in more specific questions of justice in migration, such as the permissibility of travel bans and carrier sanctions. The book also offers a particular vision about how to go beyond questions of right and liberal justice, toward a declaration of the sort of community we wish to be. The book identifies the moral notion of mercy as a central one for the moral analysis of migration; we ought to show mercy and justice in the construction of migration policy, and each of these moral norms has a role to play in public discourse.