From a global perspective, European countries have comprehensive welfare states and because of globalization processes populations of European welfare states become more “diverse”. Linking these two facts has led to a “diversity-welfare debate” in which diversity is seen as a problem for the welfare state. This problem would be higher in more developed welfare states. In this lecture, I will discuss the academic background of this debate as stemming from “warnings from the US”, I will critically discuss the term “diversity” as it used in the debate, and then address a number of empirical questions about the effect of “diversity” on welfare attitudes concerning the social rights of migrants. The main conclusion that I suggest is that there are negative attitudes towards welfare rights for migrants in European societies – but this is not worse in more diverse societies, perhaps on the contrary.