The rapid spread of large-scale and innovative social transfers in the developing world has made a key contribution to the significant reduction in global poverty over the last decade. Explaining how flagship anti-poverty programmes emerged, this book provides the first comprehensive account of the global growth of social assistance transfers in developing countries. Armando Barrientos begins by focusing on the ethical and conceptual foundations of social assistance, and he discusses the justifications for assisting those in poverty. He provides a primer on poverty analysis, and introduces readers to the theory of optimal transfers. He then shifts the focus to practice, and introduces a classification of social assistance programmes to help readers understand the diversity in approaches and design in developing countries. The book concludes with an analysis of the financing and politics of the emerging institutions and of their potential to address global poverty.