Reducing large-scale deforestation is a key objective of global efforts to mitigate climate change. An important debate concerns the levels of governance at which deforestation can be reduced effectively. Political economic theory and evidence suggests that national governments are more likely than subnational governments in agricultural frontiers to adopt restrictive forest conservation policies, due to differences in political constituencies and capacity. Here we examine the validity of this claim using an impact study of provincial-level land use planning in Argentina’s main deforestation frontier, the Dry Chaco. In 2007, Argentina’s provinces were obliged to define land use zoning for their native forests, but had considerable leeway in its implementation. We use data from 30,126 properties in the provinces of Salta, Santiago del Estero, and Chaco, and a rigorous counterfactual estimation strategy to quantify the extent to which adopted zoning plans affected deforestation. We find evidence that provincial-level land use zoning reduced deforestation in all three provinces, but not in all zones and periods. Differences in impact are associated with differences in the location of zones and the timing of planning. Our findings suggest that subnational governments can make important contributions to reducing large-scale deforestation in agricultural frontiers.