This chapter focuses on the benefits of stimulating well-being and quality of life (QOL) among athletes as a natural part of sustainable sport participation. Well-being promotion involves proactive support to help athletes develop psychosocial resources to stay functional in the sport environment and life. The historical development of well-being and QOL as a research field in sport psychology is presented. Moreover, scientific definitions, frameworks, and models commonly used in contemporary well-being or QOL research are reviewed together with examples of studies performed with elite athletes. In the final section of the chapter, future research directions and applied implications are discussed and a summarizing model is presented to stimulate future studies and applied work on well-being and QOL in sport.