Theorists of social movements and revolutions have given great attention to the factors creating vulnerability for the state – including elite divisions, loss of foreign support, and economic problems. Substantial attention has also been given to factors facilitating the mobilization of protest actors, including framing, prior network ties, social and public media, and political openings. Somewhat less evident has been the role of cross-class coalitions, which play a vital role in affecting both the strength of the state and mobilization, and in shaping the outcomes of protest and revolutionary change. If a protest draws support mainly from just one class or group (peasants, workers, students, urban shopkeepers, professionals), the state can confront that group as a disruptive force, and seek to unify elites from other sectors against that threat. However, if protestors represent many different groups, it is much harder for the state to find allies against them. Moreover, while a state can claim to be preserving society by acting against isolated disruptive elements, it is far more difficult to maintain legitimacy when acting against a broad cross-class coalition. Elites are more likely to desert the state, creating crippling elite divisions, if protestors represent a broad spectrum of society. In addition, a broad cross-class coalition facilitates further mobilization by creating ‘meganetworks’ linking prior, tightly-linked within-group networks to each other. The impact of public media in favor of the protestors is also greater if media representation shows protestors as representative of the whole society, rather than as one particular group seeking partisan advantages for itself. For these reasons, virtually all successful revolutions were forged by cross-class coalitions that bridged the diverse goals and interests of different groups, thus pitting society as a whole against the regime and its loyalist supporters. Conversely, revolts rooted in the needs and organization of one particular class or group – peasant revolts, urban uprisings, student protests, regional rebellions – have usually been effectively repressed by regimes able to draw on other groups for support. The three successful revolutions in the Arab world in 2011, in Tunisia, Egypt, and Libya, all demonstrate the crucial role of cross-class coalitions.