Citizenship As the Neighbors Do: Explaining Citizenship Policy Change in Europe

European citizenship laws have evolved significantly since World War II, especially in recent decades as more states have begun to emphasize immigrant integration. From the introduction of language requirements in countries as disparate as Portugal and Finland, to civic integration tests in the once avowedly multicultural Netherlands, to the introduction of partial jus soli in a once ethnocentric Germany, few states in Western Europe have left citizenship policy unaltered in recent years. What causes states to change their citizenship policies? Unlike previous work that focuses on historical or electoral factors, this paper departs from traditional answers to this question and situates the explanation within the growing comparative literature on policy diffusion. I argue that liberal or restrictive changes in citizenship policy in one European country inspire policy changes in neighboring countries that face similar domestic migration challenges. I then test my diffusion argument empirically with a quantitative analysis of citizenship policy change across 16 European countries since 1980. The evidence suggests that diffusion processes do shape how states adjust their citizenship policies, a finding that contributes to continuing debates among comparativists about policy diffusion across international borders.