Citizenship encompasses legal status, rights, participation, and belonging. Traditionally anchored in a particular geographic and political community, citizenship evokes notions of national identity, sovereignty, and state control, but these relationships are challenged by the scope and diversity of international migration. This review considers normative and empirical debates over citizenship and bridges an informal divide between European and North American literatures. We focus on citizenship within nation-states by discussing ethnic versus civic citizenship, multiculturalism, and assimilation. Going beyond nation-state boundaries, we also look at transnational, postnational, and dual citizenships. Throughout, we identify methodological and theoretical challenges in this field, noting the need for a more dynamic and comprehensive understanding of the inter-relationships between the dimensions of citizenship and immigration.