Book excerpt: When can contexts and diversity be resources, rather than risks, for children's developmental pathways? Scholars, policy makers, and practitioners increasingly realize that middle childhood matters as a time when children's pathways diverge, as they meet new and overlapping contexts they must navigate on their way to adolescence and adulthood. This volume shines new light on this important transition by tracing how these contexts -- cultural, economic, historical, political, and social -- can support or undermine children's pathways, and how children's own actions and the actions of those around them shape these pathways. With a focus on demographic changes taking place in the U.S., the volume also maps how experiences of diversity, reflecting culture, ethnicity, gender, and social class, matter for children's life contexts and options. Chapters by a team of social scientists in the MacArthur Foundation Research Network on Successful Pathways through Middle Childhood present the fruits of ten years of research on these issues with diverse cultural and ethnic communities across the U.S. These include: *a set of models and measures that trace how contexts and diversity evolve and interact over time, with an epilogue that aligns and compares them; *surprising new findings, quantitative and qualitative, with cases showing how children and families shape and are affected by their individual, recreational, institutional, and cultural experiences; and *applications to policy and practice for diverse children and families. The importance of these new models, methods, findings, and applications is the topic of commentaries by distinguished scholars with both U.S. and international perspectives. The book is intended for researchers, practitioners, and policy makers, as well as students in psychology, sociology, and education.