We evaluate a large-scale government reform in Peruvian public secondary schools that lengthened the school day and invested in pedagogy, staffing, and infrastructure. Using a fuzzy regression discontinuity design, we find that the program increased math and reading test scores by approximately 0.185 SD and 0.102 SD, respectively. For math only, we estimate that instructional time contributes approximately two-thirds of the effect, suggesting the importance of complementary inputs. The reform effectively enhanced school resources and increased students’ overall study time. Relative to other education interventions in Low- and Middle-Income Countries, the program delivered above-average learning gains but was relatively expensive.