<![CDATA[Background: Psychological well-being is essential for student-athletes because they must simultaneously cope with competitive sport demands and academic responsibilities. Although both sport grit and perceived psychosocial support have been associated with positive psychological outcomes, the mediating role of psychosocial support in the relationship between sport grit and psychological well-being remains insufficiently understood. Objectives: This study examined whether perceived psychosocial support mediates the relationship between sport grit and psychological well-being among high school student-athletes. Methods: A quantitative cross-sectional correlational design with a mediation analysis framework was employed. A total of 362 high school student-athletes from the first district of La Union, Philippines, participated using total enumeration sampling. Data were collected using standardized questionnaires assessing sport grit, psychological well-being, and perceived psychosocial support. Descriptive statistics, regression analysis, and bias-corrected bootstrap mediation analysis (5,000 resamples) were performed using JASP. Results: Student-athletes reported high levels of sport grit, psychological well-being, and perceived psychosocial support. Sport grit significantly and positively predicted psychological well-being, whereas it did not significantly predict perceived psychosocial support. Perceived psychosocial support demonstrated a significant but negative association with psychological well-being. Furthermore, the indirect effect of sport grit on psychological well-being through perceived psychosocial support was not statistically significant, indicating the absence of a mediating effect. Conclusions: Sport grit is an important direct psychological resource associated with psychological well-being among high school student-athletes. Although perceived psychosocial support contributes to athletes' psychological functioning, it does not explain the relationship between sport grit and psychological well-being. These findings highlight the importance of strengthening athletes' internal psychological resources while maintaining supportive sport environments.]]>
