The Multiple Indicator Cluster Survey (MICS) is a nationally representative, internationally comparable household survey implemented to examine protective and risk factors of child development in developing countries around the world. This introduction describes the conceptual framework, nature of the MICS3, and general analytic plan of articles in this Special Section. The articles that follow describe the situations of children with successive foci on nutrition, parenting, discipline and violence, and the home environment. They address 2 common questions: How do developing and underresearched countries in the world vary with respect to these central indicators of children's development? How do key indicators of national development relate to child development in each of these substantive areas? The Special Section concludes with policy implications from the international findings.