In this paper we estimate the causal effect of an extra year of schooling on mathematics skills and knowledge for the eight Latin American countries (Argentina, Brazil, Chile, Colombia, Costa Rica, Mexico, Peru and Uruguay) that participated in PISA 2012. To that end we exploit exogenous variation in students’ birthdates around the school entry cutoff date using a Regression Discontinuity (RD) design. The size of this effect may indicate the extent to which the curriculum being taught in schools at the age of 15 contributes to build the abilities needed to meet the challenges of adult life. We apply both sharp and fuzzy RD approaches to take into account the possibility of imperfect enforcement of school entry rules. Our estimates suggest strong effects of an extra year of schooling on PISA test scores for 15-year-old students, with direct implications in terms of their skills and knowledge. We compare these results to that from high-performing countries.