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α: calibrated so average coauthorship-adjusted count equals average raw count
Despite massive investments in teacher professional development (PD) programs in developing countries, there is little evidence on their effectiveness. We present results of a large-scale, randomized evaluation of a national PD program in China in which teachers were randomized to receive PD; PD plus follow-up; PD plus evaluation of the command of PD content; or no PD. Precise estimates indicate PD and associated interventions failed to improve teacher and student outcomes after one year. A detailed analysis of the causal chain shows teachers find PD content to be overly theoretical, and PD delivery too rote and passive, to be useful.