The positive youth development perspective, a strength-based relational developmental systems model that focuses on mutually influential relationships between individuals and contexts, has been used to study thriving across the second decade of life. However, more attention has been paid empirically to identifying the features of the individual (e.g., intentional self regulation, hope, or purpose) or to enumerating the role of context-general ecological assets than to the nature of individual-context relationships linked to thriving within specific contexts. The goal of this special section is to provide initial research reports about context-specific instances of the thriving process. The research focuses on two contexts where many youth spend a considerable amount, and often the majority, of their time-school and out-of-school time sports activities.