Adoption of herbicides by Ethiopian smallholders has grown rapidly, with application on cereals doubling to more than a quarter of the area under cereals between 2004 and 2014. Relying on unique data from a large-scale survey of producers of teff, the most widely grown cereal in Ethiopia, we find considerable positive labor productivity effects of herbicide use of between 9 and 18 per cent. We show that the adoption of herbicides is strongly related to proximity to urban centers, access to all-weather roads, and levels of local rural wages. All these factors have changed substantially over the last decade in Ethiopia, explaining the rapid take-off in herbicide adoption. The sizable increase in herbicide use in Ethiopia has important implications for rural labor markets, potential environmental and health considerations, and capacity development for the design and effective implementation of regulatory policies on herbicides.