Heterogeneous Naturalization Effects of Dual Citizenship Reform in Migrant Destinations: Quasi-Experimental Evidence from Europe

Does dual citizenship acceptance increase immigrants' propensity to naturalize and, if so, for whom does this matter most? We exploit exogenous variation in citizenship legislation in 200 migrant-origin countries to identify the effect of destination country policy reform. We hypothesize that the value of the origin country citizenship moderates the reform effect. We test our identification strategy in two West European countries with contrasting reforms: a canonical liberal reform in Sweden (2001) and an atypical restrictive reversal in the Netherlands (1997). We apply a staggered difference-in-differences model employing administrative data on complete migrant populations. We find reform effects remarkably similar in effect size and heterogeneity, with liberalizing reform increasing naturalization rates by 6.7 percentage points and restrictive change decreasing rates by 6.4 percentage points. The effect is concentrated among immigrants from EU and highly developed countries. Our quasi-experimental evidence informs naturalization scholarship and public debate on migrant political integration.