A comprehensive examination of the nature, causes, and consequences of internal migration in developing countriesDespite the key role of rural-urban migration in structural transformation and the persistence of lower living standards in the countryside, active policies to reduce, or even reverse, movement into towns are common in major developing regions. Climate change is shifting the calculus: the resulting erosion to agricultural opportunities, combined with increasing frequency of natural disasters, is already resulting in substantial population displacement, mostly internally and into towns in particular. Crossing the Divide examines the nature, causes, and consequences of population movements between the rural and urban sectors of developing countries. Using nationally representative, micro-level data on individuals from seventy-five countries in Africa, the Asia-Pacific, Latin America, and the Caribbean over the course of several decades, Robert E.B. Lucas moves well beyond existing studies to provide the most comprehensive and definitive treatment of internal migration currently available. Lucas analyzes these data on a country-by-country basis, considering both rural-urban and urban-rural movements, to reassess conventional understandings and offer significant new findings on who moves and who stays, the economic incentives and barriers to moving, the role of social networks, return and onward migration, and the impact of migration on families, especially children.