This study examined the self-regulatory process of moral disengagement in adolescent social bullying. Moral disengagement was assessed at the individual level, as well as within reciprocated very best friendships. At the dyadic level, this study investigated the role of friendship quality in moderating the influence of a very best friend's moral disengagement on adolescents' social bullying. The sample consisted of 710 mainly White students (306 males, 12-17 years). Results showed adolescents' proneness to moral disengagement was associated with increased social bullying. Further, a very best friend's moral disengagement was associated with higher social bullying for those who perceived positive qualities in their friendship. The findings highlight the importance of close friends in fostering adolescents' social bullying.