Self-evaluations undergo significant transformation during early adolescence, developing in parallel with the heightened complexity of teenagers’ social worlds. Intuitive theories of adolescent development, based in part on animal work, suggest that puberty is associated with neural-level changes that facilitate a “social reorientation” (Nelson, Leibenluft, McClure, and Pine, 2005). However, direct tests of this hypothesis using neuroimaging are limited in humans. This longitudinal fMRI study examined neurodevelopmental trajectories associated with puberty, self-evaluations, and the presumed social reorientation during the transition from childhood to adolescence. Participants (N = 27, M age = 10.1 and 13.1 years at timepoints one and two, respectively) engaged in trait evaluations of two targets (the self and a familiar fictional other), across two domains of competence (social and academic). Responses in ventromedial PFC increased with both age and pubertal development during self-evaluations in the social domain, but not in the academic domain. These results suggest changes in social self-evaluations are intimately connected with biology, not just peer contexts, and provide important empirical support for the relationship between neurodevelopment, puberty, and social functioning.