Grounded in self-determination theory and achievement goal theory, the purpose of this mixed-methods study was to examine the underlying motivational processes from social environments created by coaches, peers, and parents to motivational outcomes in high school athletes, with an emphasis on the relative influence of social agents in basic psychological needs (i.e., autonomy, competence, and relatedness). The quantitative part of this study tested a hierarchical model of high school sport motivation in a final sample of 311 student athletes (204 boys, 107 girls) using structural equation modeling: social factors (coach-, peer-, and parent-created motivational climates) -> psychological mediators (need satisfaction and frustration) -> types of motivation (autonomous motivation, controlled motivation, and amotivation) -> consequences (subjective vitality, athlete burnout, and intention to drop out). Invariance across gender and across team type (varsity vs. non-varsity) was also tested. Adequate model fits were achieved in separate "brighter side" and "darker side" models across the overall sample, gender, and team type. The follow-up qualitative part of this study explored "how" beyond "what" coaches, peers, and parents contribute to the social environments, need frustration, and negative motivational outcomes in sport in a subsample of 37 student athletes (24 boys, 13 girls) who reported high amotivation/burnout and higher than average dropout intentions in the quantitative survey. Content analysis and observation were conducted to interpret the focus group interview data among athletes across gender and team type. The results of both quantitative and qualitative parts were integrated and compared to summarize the roles of coaches, peers, and parents in the "brighter and darker sides" of athletic experience in high school athletes.
