This article presents evidence on the associations between family background, school characteristics and student performance in primary school in Argentina, Colombia and several comparison countries. As a general pattern, educational performance is strongly related to family background, weakly to some institutional school features and hardly to schools' resource endowments. In an international perspective, family-background effects are relatively large in Argentina, and relatively small in Colombia. A specific Argentine feature is the lack of performance differences between rural and urban areas. A specific Colombian feature is the lack of significant between-gender performance differences. Nonnative students and students not speaking Spanish at home perform particularly weak in both countries. In Argentina, students perform better in schools with a centralized curriculum and ability-based class formation.