This article exploits the sequences of the European Union (EU) enlargements to investigate their impact on the incoming countries’ agricultural policy. We use a quasi-experimental approach—the Synthetic Control method—to identify changes in the level of agricultural protection of the new members, in comparison with a counterfactual scenario. Our results suggest that earlier 1973 and 1985 EU enlargements show a significant increase in the rate of assistance to agriculture of incoming countries. The opposite holds, however, for the 1995 and 2004 enlargements, where the incomers significantly reduced their level of assistance to agriculture, in comparison with a counterfactual scenario.