This chapter offers a mechanism-based explanation of how single-cause oriented protest events are transformed into a mass movement where previously fragmented causes of contention come to be expressed in conjoint action. Drawing on the case of 2013 Gezi protests in Turkey, we map the protest waves and identify two mechanisms that mediate the influence of repression on mobilization of dissent. The first mechanism is the perceived nature of the cause of contention. Repression leads to scale shift (McAdam et al., 2008) in the first wave when exercised over those who protest for an issue perceived to be innocent. The second mechanism is the experience of repression. Boundary deactivation among protesters and the resulting continuity in protest activity follow scale shift in the second and third waves as experience of repression transforms perceptions of those that were previously framed as others. Our analysis relies on data collected via participant observation, in-depth interviews, and an online survey with 1,352 protesters.