The analysis deals with the effect of constitutional rules on agricultural policy outcomes in a panel of 74 developing and developed countries, observed in the 1955-2005 period. Testable hypotheses are drown from recent development in political economy theory that see political institutions as key elements in shaping public policies. We focus attention on both broad political reforms – i.e. democratic transitions – and on more narrow details of democracy, such as electoral rules and forms of government. Using differences-in-difference estimation we find a positive effect of a transition into democracy on agricultural protection. However, the average effect masks substantial heterogeneities across different forms of democracy. Transition into parliamentary and, especially, proportional democracy – as opposed to presidential and majoritarian – appears to produce the greatest increase in agricultural protection and support. Alessandro Olper is associate professor in the Department of Agricultural, Food and Environmental Economics at University of Milano. Valentina Raimondi is researcher in the Department of Agricultural, Food and Environmental Economics at University of Milano.