The present study, which sought to analyse adolescent sportsmen's representations of responsibility, was mainly guided by the philosophical literature on this topic. A body of literature suggests that the contextual factors of sport practice, particularly regarding the rules that regulate play, may have a key role in the building of such representations. Semi-structured interviews were conducted with two groups of 18 teenagers: one group of institutionalised athletes (who played soccer or basketball in a structured and official context) and one group of self-organised athletes (who played the same sports in a self-regulated context). The qualitative analysis showed that the institutionalised players described responsibility in functional terms; this result was explained by the rigid characteristics of their context of practice, which was based on task division and performance. In contrast, the self-organised players described responsibility in moral terms; this result was explained by an open context of practice based on interaction. The overall results of our study raise questions about the educational capacity of institutionalised sport and the objective conditions that promote the social and moral development of young people. (Contains 3 tables and 1 note.)