The present study, based on Broaden & Build theory of positive emotions, examines the relationship between study-related positive emotions and academic performance, and the mediating role of psychological capital in this relationship. A sample of 639 Chilean high school students between 14 and 17 years old was used. A s expected, a statistically significant indirect effect was found between study-related positive emotions and academic performance via psychological capital. Students’ study-related positive emotions were related to better academic performance through positive relationships with their levels of psychological capital; that is, self-efficacy, hope, optimism, and resilience (download article).