This paper examines whether additional time in elementary and secondary school affects economic well-being in adulthood. We leverage cross-municipality and cross-cohort variation in a reform that increased the Chilean school day by 30 percent between 1997 and 2010 and find that full-day schooling increased educational attainment, delayed childbearing, and increased earnings when students reached young adulthood. These findings are consistent with a human capital channel and demonstrate large-scale investments in public education can yield long-term economic benefits.