This Paper utilizes a unique dataset on votes cast by Czech and Polish migrants in their recent national elections to investigate the impact of institutional, political and economic characteristics on migrants’ voting behaviour. The political preferences of migrants are strikingly different from those of their domestic counterparts. In addition, there are also important differences among migrants living in different countries. This Paper examines three alternative hypotheses to explain migrant voting behaviour: adaptive learning; economic self-selection and political self-selection. The results of the analysis suggest that migrant voting behaviour is affected by the institutional environment of the host countries, in particular the tradition of democracy and the extent of economic freedom. In contrast, there is little evidence that differences in migrants’ political attitudes are caused by self-selection based either on economic motives or political attitudes prior to migrating. These results are interpreted as indicating that migrants’ political preferences change in the wake of migration as they adapt to the norms and values prevailing in their surroundings.