This article explains the effects of ethnic nationalism on Anglophone and Francophone migration. The rise of Québec ethnic nationalism in the 1960s dismantled the cultural division of labour, which created new opportunities for Francophones but threatened Anglophones' traditional dominance over the Québec economy. This had negative consequences for Anglophones but positive outcomes for Francophones, which in turn accounts for differences in migration patterns. Drawing from the internal colony model as well as migration and exit‐voice theories, and using ecological census data, micro‐census data and election panel data, I find that the key variables that increase the likelihood of Anglophone out‐migration either do not explain Francophone out‐migration or have opposite effects. This is because ethnonationalist policies decreased the economic return particularly for well‐educated, higher‐earning, professional Anglophones in Québec, while increasing the economic position of Francophones and in particular well‐educated professionals.