This book is a product of an empirical research project, begun in 2006, aimed at improving our understanding of the extent, causes, and effects of government interventions in global agricultural markets over the past five decades. The first stage of the project generated analytical narratives of the evolution of policies for a sample of seventy-five countries that together account for between 90 and 96 percent of the world's population, farmers, agricultural output, and total GDP. In each country case study, the narrative was informed by the authors' new estimates of distortions to agricultural incentives caused by price, trade, and exchange rate policies. Annual estimates for nominal rates of assistance and consumer tax equivalents were provided for more than seventy different farm products, with an average of eleven per country that represented around 70 percent of the gross value of agricultural production in each focus country. Estimates of the overall rate of government assistance to agriculture relative to that for nonfarm tradable goods also were provided. The country studies are reported in four regional volumes and a global overview volume that were published by the World Bank in 2008–09, along with the global database of price distortions. They were followed by another volume, published in early 2010, that focused on quantifying the effects of current distortions on global welfare, inequality, and poverty.