In his career of more than half a century, Haberler made important contributions advancing the discipline of economics, especially in international trade and development. His work in the areas of comparative advantage and the welfare implications of free trade and protection has had a major influence on trade policy, and in turn has affected the course of development economics. This book contains lectures which, spanning over thirty years - the Cairo lectures of 1959 and the 1987 Pioneers lecture with comments by W. Max Corden and Ronald Findlay - demonstrate the timeless nature of Professor Haberler´s analysis and policy recommendations.