Sport program structures have been shown to directly influence outcomes associated with youth sport participation (Baldwin & Wilder, 2014), including mental health (Durlak et al., 2010). However, there is limited research on the specific mechanisms that facilitate or hinder mental health in this context. The purpose of this study was to examine the relationships between perceived program quality, basic needs satisfaction, and mental health within youth sport. Youth participating in sport programs (N = 160; Mage = 15.36, SD = 2.50) completed validated paper questionnaires at mid-point in their sport program, with questions related to the quality of their sport program, and at end-point in their sport program, with questions pertaining to basic needs satisfaction and mental health. Structural equation modeling was used to test the direct relationships between program quality and mental health and between basic needs satisfaction and mental health. Using a variety of fit indices, results revealed an adequate fit of both models to the data, suggesting that program quality significantly and positively predicted basic needs satisfaction and basic needs satisfaction significantly and positively predicted mental health. Bootstrapping analysis was used to test if basic needs satisfaction mediated the relationship between program quality and mental health. Results supported mediation, with a large effect (k2 = 0.28). These findings emphasize the value of structuring youth sport programs to satisfy basic needs, which can have positive implications on mental health. This is important because mental health in childhood may translate into mental health in adulthood.