The World Bank work program on rural-urban transformation, co-sponsored by the Poverty Reduction and Economic Management (PREM) Network and Sustainable Development (SD) Network vice presidencies, spanned two years, from mid-2008 to mid-2010, and benefited from the contributions of development analysts and practitioners from the World Bank and other international organizations and academic institutions. The authors would like to thank the Poverty Reduction and Equity Group, led by Ana Revenga, sector director, Jaime Saavedra, sector manager, and Louise Cord, former sector manager, and the Finance, Economics, and Urban Department, led by Zoubida Allaoua, sector director, for their ongoing support of this work program. Special thanks go to Marisela Montoliu, who initiated the cross-sectoral work program as head of the Spatial and Local Development team in the SD Network. Her intellectual leadership and hands-on engagement throughout the research and writing process-including her own contribution of the overview chapter-enhanced the relevance and impact of the work program. The authors also gratefully acknowledge the substantial contributions of the panel of peer reviewers