This article by Leandro Vergara-Camus features in the World Social Science Report 2016. This contribution examines our academic and political understandings of social movements, and the ways in which social movements in the developing world have recently tackled social inequalities and struggled for social justice. It highlights the importance of social mobilization, and critically examines the relationship between movements, political parties and the state. Constitutional moments are shown to be crucial for the establishment of an agenda and a discursive framework enabling the development or the critique of state policies. The author concludes by advising against romanticizing social movements, but recognizes the essential role that they play when they are relatively autonomous from the state.