Economic success-among individuals, firms, products and countries-is often unexpected and unpredicted. William Easterly will draw on insights from Nobel laureate Friedrich Hayek to explain why prediction is difficult, success is rare and failure is common; the advantages of decentralized decision making to discover what works best in the market and in public policy; and the need to rely on dispersed and local knowledge, rather than government planning, for poor countries to achieve growth. Arvind Subramanian will draw on his experience working at multilateral institutions to comment on the relevance of Hayek’s insights to developing countries and the current foreign aid debate.