There is growing awareness of the common difficulties experienced by poor young people who grow up in cities—crime and juvenile delinquency, limited access to education, the spread of infectious diseases, homelessness, and high rates of unprotected sex. They must contend with weak families and social institutions, poor labor market prospects, and for the most unfortunate, the ravages of gang war and the HIV/AIDS epidemic. Chapters in this volume present and assess comparative evidence on the well-being of urban youth and proven interventions for assuaging the deleterious effects of poverty.