We use a large-scale randomized experiment (across 1,198 public primary schools in Mexico) to study the impact of providing schools directly with high-quality managerial training by professional trainers vis-à-vis through a cascade-style “train the trainer” model. The training focused on improving principals’ capacities to collect and use data to monitor students’ basic numeracy and literacy skills and to provide feedback to teachers on their instruction and pedagogical practices. After two years, the direct training improved schools’ managerial capacity by 0.13σ (p-value 0.018) (relative to “train the trainer” schools), but had no meaningful impact on student test scores (we can rule out an effect greater than 0.08σ at the 95% level).