Students' academic engagement is considered as an important predictor of academic outcomes. Hence, it is necessary to pay attention to the factors influential on it. The present study was carried out to longitudinally investigate some variables, effective on students' academic engagement. So, 391 students (49. 4% females and 50. 6% males) were selected from high schools in the city of Tehrān, based on the random cluster sampling method. The participants completed measures of self-compassion (Neff, 2003), adolescents' basic psychological needs (Tian et.al, 2013), social safeness (Gilbert et.al, 2009), and student engagement (Viega, 2016) at two time points, with 4 weeks interval. Cross-lagged panel structural equation modeling was used to analyze the data. The results showed that self-compassion has direct and positive effect on student engagement over time. Furthermore, self-compassion via basic psychological needs and social safeness indirectly and positively affected the students' academic engagement. These findings provided empirical support for better understanding of mediating mechanisms of the relationship between self-compassion and the students' academic engagement. Implications and future research directions would be discussed.