In this work we examine the development of citizenship laws in the world. Our analysis is based on a databank we compiled that documents this development for 162 countries in the period 1948-2001. On the basis of an econometric study our results can be summarized as follows. The original juridical tradition – the application of the jus soli rather than the jus sanguinis – continues to have an effect on current legislation. The pressure of migration tends to limit how open the legislation is, restricting the application of the jus soli. One of the factors determining greater openness is the degree of democracy and demographic stagnation. only subscribers can see the full article