Conventional thinking maintains that people can belong to only one society and can be loyal to only one nation-state. In a world with rising rates of trans-national migration, however, the possibility of participation, belonging, and loyalty to more than one state is ever more evident. This has led to a rethinking of the notion of nation-based citizenship and increased tolerance toward holding citizenship in more than one country. In practice, over half of the world's nation-states currently recognize some form of dual citizenship or dual nationality. This book focuses on clarifying and comparing how the rules of acquisition, maintenance, and revocation of dual citizenship have been modified and justified in eight states associated with the European Union: Estonia, Finland, France, Germany, Greece, Israel, Portugal, and the United Kingdom. The main question is: How have the rules of attribution, loss and/or acquisition of dual citizenship been modified and justified in these eight states? Viewed in the context of international covenants, legislation regarding dual and multiple citizenship is analyzed in terms of how it is made tangible in juridical, social, cultural, and educational domains.