Latin America witnessed a resurgence of protests during the 1990s and early 2000s. Citizens took to the streets to protest against the liberalization of public services and rising levels of inequalities and poverty. This situation partly changed in the decade of the 2000s when the region experienced a period of sustained social policy expansion intended to extend protections to formerly excluded groups. Did popular mobilization have an influence on the turn toward universalism in Latin American social policy? This paper explores this question by looking at the relationship between protest, the strength of the Left and the adoption of expansive reforms in healthcare, conditional cash transfers and noncontributory pensions. The findings bring support to the idea that protest is a relevant aspect of the politics of social policy reform, although its effects are both sensitive to other characteristics of the political environment and the particular policy dimension considered.