Billions of government dollars, and thousands of charitable organizations and NGOs, are dedicated to helping the world's poor. But much of their work is based on assumptions that are untested generalizations at best, harmful misperceptions at worst. Abhijit Banerjee and Esther Duflo have pioneered the use of randomized control trials in development economics. Work based on these principles, supervised by the Poverty Action Lab, is being carried out in dozens of countries. Drawing on this and their 15 years of research from Chile to India, Kenya to Indonesia, they have identified wholly new aspects of the behavior of poor people, their needs, and the way that aid or financial investment can affect their lives. Their work defies certain presumptions: that microfinance is a cure-all, that schooling equals learning, that poverty at the level of 99 cents a day is just a more extreme version of the experience any of us have when our income falls uncomfortably low. This important book illuminates how the poor live, and offers all of us an opportunity to think of a world beyond poverty.