Abstract: | While the concept of citizenship has received considerable scholarly attention in recent years, few studies focus on the increasingly prevalent reality of dual citizenship, or full membership – with its respective rights, privileges, and obligations – in two different countries. The main objective of this article is to conceptualize, measure, and classify variation in dual citizenship in the countries of the European Union. I start by recounting the historical opposition to dual citizenship and by describing its emergence in recent decades. I then develop a “Citizenshi Policy Index” that accounts for some of the intricacies associated with citizenship policies in general and dual citizenship policies in particular. I go on to apply these measures to the fifteen “older” EU countries in both the 1980s and the contemporary period – thus allowing for an analsis of the changes that have taken place over the past two decades members. Overall, the findings point to surprisingly resilient national differences that stand out in contrast to the EU's institutional “harmonization” in so many other areas. |