This article surveys the practice of dual nationality in the Western Hemisphere, particularly as it impacts the naturalization rates of immigrants in the United States. The article begins by looking at the extent and spread of dual nationality provisions and the pathways for its implementation. Next, the article turns to a discussion of the multiple (and at times conflicting) interests – of immigrants, sending states and receiving states – in dual nationality. While immigrants and sending countries are in general agreement on the positive benefits of dual nationality, commentators in receiving countries like the United States continue to express deep unease at the spread of dual nationality and its consequences for American citizenship. Are these concerns justified? Not according to U.S. naturalization rates. Data from 1965 to 1997 indicate that immigrants from countries recognizing dual nationality average higher naturalization rates in the United States than countries that do not.