The results of numerous studies indicate that besides intellectual abilities, personality features figure as the strongest predictors of academic achievement. This research is aimed at exploring the relationship between personality features and academic achievement in secondary school students, as well as at testing whether academic achievement is one of the mechanisms suitable for explaining the relationship between personality features and the subjective well-being of students. The research included 408 students, with the average age of 16 years and 6 months. The results indicate that in both girls and boys a significant predictor of academic achievement is only the feature of conscientiousness. However, in conscientious students, higher academic achievement does not yield higher satisfaction with school and life, nor more frequent experiencing of pleasant emotions. Academic achievement is neither connected with openness towards experience nor with curiosity. The paper discusses practical implications of these findings and offers suggestions for future research. [Ministarstva nauke Republike Srbije, br. 179006: Nasledni, sredinski i psihološki činioci mentalnog zdravlja i br. 179022: Efekti egzistencijalne nesigurnosti na pojedinca i porodicu u Srbiji]