16 December 2021In this article we aim at quantifying the impact of the crop diversification measure implemented in France as part of the 2013 CAP greening reform. While numerous studies assess the impact of the measure using simulation models, none uses causal treatment methods or ex-post data. We exploit a discontinuity in the constraints imposed on farms over and under 30ha, respectively, and apply an OLS-FE method with a regression discontinuity setup on land use data collected from a representative sample of French farmers before and after reform implementation. We find that the crop diversification measure increases both compliance with the measure and the number of crops grown by farms greater than 30ha. Furthermore, graphical analyses suggest that farms over and under 30ha responded differently to the reform.