The index analyses naturalization policies in twenty-six Western immigrant-receiving democracies in order to show how different countries deal with newcomers (year of reference: 2009). The index looks at five aspects of a country’s citizenship and naturalization policies. First, it considers whether a country grants automatic citizenship only to children of citizens (ius sanguinis) or only to those who are born within the country’s border (ius soli). Second, every naturalization policy stipulates that immigrants have to have lived at least a certain number of years within the borders of the country before they can apply for citizenship. Third, it looks at whether passing a language test is part of the naturalization requirements. These tests vary significantly in difficulty. Fourth, in some countries immigrants cannot be naturalized without passing a citizenship test, while in other countries such a test does not exist. Moreover, these tests vary in nature. Fifth, and finally, it includes whether immigrants are required to give up their former nationality or nationalities before they can become citizens. These five scores are combined in an index that ranges from 0 to 15. Overall, this summary score should give a valid indication of the exclusiveness, or ‘ethnicness’, of a country’s naturalization policy.