The Annual World Bank Conference on Development Economics 2011: Development Challenges in a Post-crisis World (ABCDE) presents papers from a global gathering of the world’s leading development scholars and practitioners held May 31 - June 2, 2010. Paper themes include: Environmental Commons and the Green Economy, Post-crisis Development Strategy, the Political Economy of Fragile States, Measuring Welfare, and Social Programs and Transfers. Keynote addresses: Elinor Ostrom: Overcoming the Samaritan"s Dlimemma in Development Aid -- Torsten Persson: Weak States, Strong States, and Development -- Joseph Stiglitz: Learning, Growth, and Development -- Partha Dasgupta: Poverty Traps --