This paper provides an historical overview of both the evolution of the economic performance of the developing world and the evolution of economic thought on development policy. The twentieth century was broadly characterized by divergence between high-income countries and the developing world, with only a limited number (less than 10% of the economies in the world) managing to progress out of lower or middle-income status to high-income status. The last decade witnessed a sharp reversal from a pattern of divergence to convergence - particularly for a set of large middle-income countries. The latter phenomenon was also driven by increasing economic ties among developing countries and, on the intellectual scale, increased knowledge generatio...