This article argues that autocratic regime strength plays a critical mediating role in the link between economic development and democracy. Looking at 167 countries from 1875 to 2004, I find that development strengthens autocratic regimes, as indicated by a reduced likelihood of violent leader removal. Simultaneously, greater development predicts democratization, but only if a violent turnover has occurred in the recent past. Hence, development can cause democratization, but only in distinctive periods of regime vulnerability. Although development’s stabilizing and democratizing forces roughly balance out within autocracies, they reinforce each other within democracies, resolving the puzzle of why economic development has a stronger effect on democratic stability than on democratization. Further, the theory extends to any variable that predicts violent leader removal and democracy following such violence, pointing to broad unexplored patterns of democratic development.