Europe has become an immigration continent. Yet the rights of immigrants and their access to citizenship differ widely between its nation-states. This collection of essays looks into the following questions: What is the legal status assigned to immigrants in the different European states? Under which conditions can foreigners become naturalized? Do traditional definitions of national citizenship sufficiently take into account new patterns of migration in this area? Is the new citizenship of the European Union a first step towards a supranational political membership and how will it affect immigrants from other countries? Will dual citizenship be seen as an adequate legal expression of multiple social ties that connect migrants to societies of destination and origin? What can be learned from the experience of nations built from immigration, such as Canada and Australia? Finally, the normative issues are addressed: How much cultural adaptation should be involved in naturalization