Background: This study examined students' perceptions of autonomy-supportive teaching (AST) and its relations to internalization of pro-social values and bullying in class. Aims: We hypothesized that: (1) teachers' AST, which involves provision of rationale and taking the student's perspective, would relate positively to students' identified internalization of considerateness towards classmates, and would relate negatively to external regulation (considerateness to obtain rewards or avoid punishments); (2) students' identified regulation would relate negatively to self-reported bullying in class, whereas external regulation would relate positively to bullying; and (3) the relation between teachers' AST and student bullying would be mediated by students' identification with the value of considerateness towards others. Sample: The sample consisted of 725 junior high school students (50% females) in Grades 7 and 8 from 27 classes in four schools serving students from lower-middle to middle-class socioeconomic backgrounds. Method: The participants completed questionnaires assessing the variables of interest. Results: Correlational analysis supported the hypotheses. Moreover, mediational analyses using hierarchical linear modelling (HLM) demonstrated that identified regulation mediates the negative relation between AST and self-reported bullying in class. The mediational hypothesis was supported at the between-class level and at the within-class level. Conclusions: The findings suggest that school policy aimed at bullying reduction should go beyond external control that involves external rewards and sanctions and should help teachers acquire autonomy-supportive practices focusing on students' meaningful internalization.