Five years on from the protests that forced Egypt’s Hosni Mubarak from power, the hopes of Tahrir Square are unfulfilled. Indeed, rather than beginning to transition toward democracy, Egypt has been backsliding toward dictatorship. What factors determine whether a nation under authoritarian rule—in Tunisia, Myanmar, Cuba, Venezuela, or several Middle Eastern nations—will succeed in transitioning to sustainable democracy? What lessons can today’s reformers learn from those who have succeeded in making such transitions in recent decades?