Causal evidence on the effectiveness of management in education is limited and ambiguous. In this study, we investigate how cost-effective management practices boost student learning through a randomised field experiment conducted with 31,760 students from 80 grade 1–9 public schools in the municipality of Rio de Janeiro, Brazil. The experiment intervention, delivered by municipal servants exclusively to school managers, involved one-to-one coaching and on-the-job training focused on implementing the World Management Survey (WMS)’s “23 best management practices” for the education sector. We also conducted two double-blind, in-depth management surveys, one prior to and one following the programme implementation, to evaluate precisely the quality of the management of the schools. The surveys were based on the WMS methodology. After two years, the estimated average treatment effects were 0.928 (0.260) SD for school management, 0.226 (0.059) SD for reading, and 0.237 (0.059) SD for mathematics. Instrumental variable estimates indicate that a one-point improvement in school management (on a 1—5 scale) led to gains of 0.680 (0.245) SD in reading and 0.714 (0.265) SD in mathematics. Students in schools achieving a one-point management improvement were more than two academic years of learning ahead of peers in untreated schools. We present causal estimates amongst the largest in the education intervention literature based on a programme that costs only $15.22 (PPP-adjusted) per student per year. The programme can be applied to any school and has expanded in Brazil. JEL Codes: C93, H83, I20, J24 and M10.