Popular perceptions of a state's legitimacy are inextricably bound to its ability to rule. Vast military and material reserves cannot counter the power of a citizen's belief, and the more widespread the crisis of a state's legitimacy, the greater the threat to its stability. Even established democracies such as France and India are losing their moral claims over society, while highly illiberal states such as China and Iran enjoy strong showings of public support. Gilley's unique approach merges a broad study of legitimacy and performance in seventy-two states with a detailed empirical analysis of the mechanisms of legitimation. The results are tested on a case study of Uganda, a country that, after 1986, began to recover from decades of civil war. Considering a range of explanations of other domestic and international political phenomena as well, Gilley ultimately argues that, because of its evident real-world importance, legitimacy should occupy a central place in political analysis.