This is the fourth of five volumes summarizing the results of the World Bank research project 'A comparative study of the political economy of agricultural pricing policies'. The volume provides a comparative analysis of the findings from the 18 country studies and deals specifically with the economic aspects of agricultural price intervention. Together with the fifth volume, it provides a synthesis of the 18 country studies undertaken in this research project. The purpose of the project was threefold: (i) to provide systematic estimates of the degree of price discrimination against agriculture within individual countries; (ii) to determine how this intervention affected such key variables as foreign exchange earnings, agricultural output, and income distribution; and (iii) to gain further insight into the political economy of agricultural pricing policy. This volume is divided into four sections focusing on historical patterns of price intervention, output, consumption and trade effects of price intervention, consequence of price intervention on income transfer and equity, and determinants of agricultural taxation.