Voluntary land registries can affect land use by facilitating both the public's ability to monitor land use and farmers' access to credit. We estimate the impacts of participation in a land registry on the conversion of natural vegetation to agricultural land use by examining the impacts of the rural environmental registry (CAR) in Brazil, using a dynamic land use model. We show that although participation in the CAR does not significantly affect crop area, it does influence pasture expansion, with variation by farm size and environmental compliance level. Our results provide insights for agricultural land‐use policies by illuminating how the intended environmental objectives of land registry programs might be undermined by credit policies.