The expansion of social pensions in Latin American countries was part of a larger process aimed at equalizing protections between formal sectors workers and outsiders. These reforms were enacted by governments of different colours, and varied considerably with regard to the scope of the new programmes. While previous studies have privileged economic factors and political ideology to explain these differences, this article extends these frameworks to look at the effect of protest on reform outputs. It uses a two-step qualitative comparative analysis to investigate the influence of protests on reforms extending the coverage of social pensions under different constellations of political, economic and institutional conditions in 18 Latin American countries (2000-2011). The results show that protest is a quasi-necessary condition in almost all configurations of expansion, but that its effect is contingent on the ideology of governments, the levels of political competition and the strength of unions.