Background: Mid-adolescence is an important phase of self-development in various domains including academics as well as for changes in the neural mechanisms underlying the self-concept. Students' academic self-concept (ASC) is affected by educational achievements and social others (such as teachers and peers). To what extent these external influences relate to neural dynamics during adolescents' self- and other-evaluations (i.e. of friends and teachers) which affect ASC over time is currently unclear. Aims: The current study aimed to address the question of to what extent the developing ASC is influenced by developmental changes in self- and other-evaluations (friends, teachers) and their underlying neural mechanisms as well as academic achievement. Methods: In this interdisciplinary longitudinal fMRI study, forty-seven 13-year-olds (at T1) were instructed to indicate whether positive and negative trait adjectives described themselves (self-evaluations), their teachers, or peers (other-evaluations) at two time points. We investigated how adolescents' academic self-concept is influenced by changes in their academic achievement and self- and other-evaluations (teachers and peers) 1.5-years later. Results: Behaviourally, both, academic achievement and positive teacher evaluations were important to prevent the observed decline in ASC during mid-adolescence. Our fMRI results showed that cortical midline structures were linked to self-evaluation, whereas the precuneus and occipital regions were related to friends- and teacher-evaluation. Here, ASC was predicted by activity changes in the precuneus during friends-evaluations for students with better academic achievement. Conclusion: Our findings indicate that academic achievement and positive teacher-evaluations could prevent the decline in ASC observed in mid-adolescents and that the neural correlates of evaluating close others within the precuneus present an important link to ASC. The current study highlights the importance of educational neuroscience studies to understand the changing ASC during adolescence.