We study the political economy of instrument choice in OECDs agricultural and food policies. After a review of the historical evolution of Western Europe agricultural price and trade policy instruments since 1880, we develop a simple political economy model of instrument choice. The key predictions of the model suggest a rational explanation of instrument choice patterns, based on the tradeoff between the different costs component of the policy, imperfect information about future market conditions, and internal and external political constraints. A formal empirical analysis on OECD countries gives broad support to the main predictions of the theoretical model. Alessandro Olper is associate professor in the Department of Agricultural, Food and Environmental Economics at University of Milano. Johan F.M. Swinnen is professor in the Department of Economics at Catholic University of Leuven and director of LICOS (Centre for Institutions and Economic Performance).