Knowledge about mass political attitudes and behavior derives mainly from studies of established Western democracies. But do populations under autocracy engage in the political process and, if so, do they support or challenge the status quo? Much depends on the nature of political regimes. To the extent that spaces for political expression are closed under autocracy, citizens face an unpalatable choice between political acquiescence and violent protest, with all the risks that such options impose. A key question for researchers is whether participants in authoritarian politics are active citizens or mobilized subjects. Survey evidence suggests that some people may be willing to grant legitimacy to strong leaders and to trust the institutions of a dominant state. Others nevertheless find ways to engage in conventional political behaviors such as discussing public affairs, taking collective action, and turning out to vote in elections, especially under hybrid competitive authoritarian regimes. Under what conditions do citizens sometimes rebel against entrenched authority? Regime type again seems to matter, with popular protest more common under open than closed systems. With reference to prodemocracy social movements, like the Arab Spring of 2011, analysts debate whether people take to the streets principally for reasons of rational self-interest or propelled by emotions like anger. And scholars explore the effects of new information and communications technologies, finding mixed results for political mobilization. As emphasized in the literature on contentious politics, the displacement of autocratic regimes from below is likely only if social movements build strong and sustained political organizations.