Evidence of the impact of community-based forest management (CBFM) on conservation outcomes is mixed. Local governance is a key moderating factor, but what constitutes good governance is still up for debate. Desirable institutional features typically arise endogenously, which complicates the analysis of causality. We use an experimental design to analyze the impact on environmental outcomes of adding an externally implemented monitoring regime to an existing CBFM initiative in Ethiopia. We distinguish between bottom-up and top-down monitoring to improve the accountability of local leaders. We find that enhanced bottom-up monitoring by community members does not affect forest outcomes, but top-down monitoring promotes forest conservation. We also identify a mechanism linking top-down monitoring to conservation: leaders work harder to protect the forest, which “crowds in” effort by community members. Our results are not about reducing the role of communities in forest management, they are a plea for oversight by the relevant authority to help communities overcome local power asymmetries.