In this study of young adolescents' (N = 188, M age = 11.93, 54.8% females) body dysmorphic disorder (BDD) symptoms, we examined a theoretically-derived model to determine if symptoms could be explained by appearance-related teasing, general peer victimization, and social anxiety. BDD symptoms were assessed as distressing preoccupation with perceived appearance defects, social avoidance, and repeated grooming and appearance checking. Associations were expected to occur via the social-perceptual bias known as appearance-based rejection sensitivity (appearance-RS). The source of appearance teasing was also considered (same-sex vs. cross-sex peers), and age and gender moderation were assessed. As predicted, in a structural equation model, BDD symptoms were higher when adolescents self-reported more appearance teasing and higher social anxiety. Moreover, it was appearance teasing by cross-sex peers, rather than same-sex peers, that was uniquely associated with elevated BDD symptoms. These associations were partially mediated by appearance-RS. Notably, peer-reported general victimization was not associated with BDD symptoms. There was no evidence for gender moderation, but some age moderation was found, with stronger associations usually found among older compared to younger adolescents. The findings suggest that appearance-related social adversity, particularly cross-sex teasing, is linked with greater concerns about rejection due to appearance and, in turn, heightened BDD symptoms. This has important implications for understanding the development and treatment of BDD. Continued research to identify the social experiences and interpretative biases that contribute to BDD symptomology is needed.