The role of community in child and adolescent development is emerging as a significant area of theoretical inquiry, research, and application. This article describes the development and utilization of a comprehensive community change effort designed to increase the attention of all community members toward strengthening core developmental processes for children and adolescents. It describes the development of 2 theoretical constructs, that of developmental assets and of asset-building communities. It presents a conceptual overview of both constructs, a descriptive account of the developmental assets within a large aggregate sample of approximately 99,000 sixth to twelfth graders, and a summary of change strategies shaping asset-building movements in over 200 communities. (Contains 4 tables, 2 figures and 10 footnotes.)