In this chapter we review the main perspectives on democratization and then propose an analytic organization of the different roles that social movements, trade unions, advocacy networks, churches, and cycles of protest play in the dynamic, contingent, and contentious shaping of democracy. In doing this, we are of course not pleading for an exclusive focus on democratization “from below”; we are convinced that the path and speed of democratization processes are influenced by the strength and characteristics of several social and political actors. The combination of protest and consensus is in fact a main challenge for democratization processes. We suggest, however, that social movements are often important actors in all stages of democratization. In our discussion of these topics, we draw examples especially from Latin America, Southern Europe, and Eastern Europe.