Since 1993, all nationals of the EU Member States hold EU citizenship, which entails the right to move and reside freely within EU territory. Since 1999, immigration has been a matter of shared competence between the EU and its Member States. The EU increasingly faces the question whether this common immigration policy as well as the common status of EU citizenship do not also require harmonization of the rules on acquisition and loss of nationality, or even the transfer of national competences to the EU, because the nationality law rules of individual Member States can be used to circumvent the common EU migration policy. In fact, a considerable number of Member States grant particular groups of people (former emigrants and their descendants living outside the EU, co-ethnics in neighbouring countries that are not part of the EU) facilitated access to their nationality and also encourage dual nationality. The link of these ‘external EU citizens’ with the EU is often very weak. At the same time, there are large numbers of EU resident people who continue to suffer the hardship of being stateless because they cannot qualify for the nationality of an EU Member State. Both the facilitated access to the EU through dual nationality and the vulnerable position of EU resident stateless persons gives the EU a strong interest in interfering with Member State autonomy in nationality law.The proposal will study global trends regarding dual nationality and statelessness by investigating how North America, and to a lesser extent Latin America, deal with these phenomena. For that purpose, research missions will be conducted on both continents. The results are compared with European data already collected by the applicant and the EUDO citizenship project. As nationality law will increasingly become a policy concern to the EU, the applicant’s global research will contribute to both the academic and policy-orientated debate on the future role of the EU in matters of nationality law.