AbstractFor students, high school sport represents a meaningful activity to develop relationships (Camiré, 2015), increase connection to school (Camiré, 2014), foster health-conscious decision-making (Van Boekel et al., 2016), develop athletic talents (Gould & Carson, 2008), and learn life skills (Camiré & Kendellen, 2016). To better apprehend the outcomes of participation, the associations between the coach-athlete relationship, athletes' basic psychological needs satisfaction, and life skills development were examined. A total of 1238 high school coaches (males = 728, 59%) from Alberta (n = 672), British Columbia (n = 474), and Newfoundland and Labrador (n = 92) were recruited. Coaches (Mage = 55.91; SD = 11.76) completed an online questionnaire in February-March 2018, which included demographic questions, the Coach-Athlete Relationship Questionnaire (CART-Q; Jowett & Ntoumanis, 2004), the Interpersonal Behaviors Questionnaire (IBQ; Rocchi et al., 2016), and the Life Skills Scale for Sport (LSSS; Cronin & Allen, 2017). Confirmatory factor analyses indicated good model fit for all scales (Hair et al., 2010; CFI 0.08, RMSEA > 0.05, and X²/df > 5). A mediation analysis using structural equation modeling tested (a) whether an association existed between CART-Q and LSSS outcomes and (b) whether the association between CART-Q and LSSS outcomes was dependent on the satisfaction of athletes' basic psychological needs. Results indicated the coach-athlete relationship was directly related to athletes' emotional and social skills and indirectly related to teamwork, goal setting, problem solving, leadership, time management, and communication through the satisfaction of athletes' basic psychological needs.