This thesis collects two essays that investigate how nativesâ attitudes to- wards immigration shift and the political implications of such a change. In chapter 2 we look at the role these attitudes play in the the electoral suc- cess of right-wing nationalist parties. We model the electoral competition between a nationalist and status quo party who differ on immigration policy. In a probabilistic voting model voters are not only swayed by the material impact of policy for themselves - they also have an individual attitude to- wards immigration that informs their voting decision. We find that the trend towards nationalist populist policies can be explained both by voters turning against immigration and by a rise in income inequality. In chapter 3 we assess empirically what may cause the kind of change in attitudes that promotes such populist behaviour. We exploit the differential impact of the 2015 Eu- ropean refugee crisis using a difference-in-differences model to identify the causal impact of the crisis on attitudes. Using data from the European So- cial Survey that measure how respondents feel about the economic, cultural and the overall impact of immigration we find that the crisis increases natives concerns and widens the polarisation of attitudes towards immigration across cultural lines. Linked to our model in chapter 2 we find that for voters who voted for populist parties in the previous election the increase in negativity towards immigration is dramatically larger. We also find some evidence that if respondents are more likely to have had contact with immigrants in the past then the crisis causes a less negative shift in attitudes.