Various traditions within developmental science and psychology have concentrated on either personal or collective correlates as manifestations of well-being. The authors' claim is that the well-being of any one person is highly dependent on the well-being of her relationships and on the community in which she resides. Well-being may be defined as a positive state of affairs in which the personal, relational, and collective needs and aspirations of individuals and communities are fulfilled. Well-being refers to a satisfactory state of affairs for individual youth and communities that encompass more than the absence of risk. The authors' definition of well-being is in line with comprehensive conceptualizations of health promotion and youth development that emphasize the values of self-determination, participation, community capacity-building, structural determinants, and social justice. In this article, the authors introduce a framework for understanding well-being in general and the well-being of youth in particular. In addition, they offer a model for analyzing interventions designed to promote personal and collective well-being. Finally, they discuss the contributions of the authors of this special issue to their analytical and intervention frameworks. (Contains 1 table and 2 figures.)