Core social movement research argues that large-scale challenges to authority build upon preexisting organization and civil society resources. How do dissenters mobilize masses in repressive settings where, given curtailment of civil society, autonomous associations scarcely exist and norms discourage trust more than encourage it? Testimonials from the Syrian uprising illustrate how protest can become widespread under such conditions, yet occurs through processes different from what dominant theory expects. Activists get demonstrations off the ground by planning around awareness of their organizational deficits. Once in motion, contention propels both organization and increasing organizational sophistication. To be effective, mobilization sometimes evades or obscures established social relationships, even as it produces new forms of sociability. Bridging literatures on mass and clandestine mobilization, this research reconsiders the assumed sequential logic of movement development from organization to protest, rather than vice versa. It also shifts attention from movement antecedents toward the resourcefulness and strategy that enable mobilizing both from scratch and at grave risk.