How do social movements sustain themselves under authoritarian rule? This remains a crucial puzzle for scholars of comparative politics. This article gains traction on this puzzle by foregrounding the generative power of protest, namely the power of protest experiences themselves to deepen and broaden movements. Some studies have started to draw attention to those questions without yet systematically examining how the form of protest differentially affects those outcomes. I argue that different forms of protest have varying effects on movements depending on their duration and geographic scope. While short, multiple-site actions, such as marches, can broaden movements by expanding their base, extended, single-site actions, such as sit-ins, are more likely to deepen movements by fostering collective identities and building organizational capacities. This article is based on field research in Egypt, Tunisia, Jordan, and Morocco and interviews with more than 100 movement participants and civil society activists.