I address the role of social mobility in political transitions. I develop a political economy model of regime transitions that incorporates social mobility as a key feature of the economy capturing the political attitudes toward redistribution. I show that social mobility facilitates democratization by reducing the conflict over redistribution between the rich and the poor. Furthermore, it facilitates democratic consolidation by reducing the likelihood of a coup under democracy. On the other hand, social mobility helps to keep an authoritarian regime stable by reducing the likelihood of mass movements against political elites. Copyright © 2005 Sage Publications.