This chapter explores the psychological and contextual factors influencing individuals’ acceptance of responsibility to intervene in bullying and peer victimization. Drawing from the theory of reasoned action, it emphasizes the roles of personal attitudes and perceived social norms in shaping one’s sense of responsibility. The individual variables of personal attitudes, moral disengagement, empathy, perceived severity of victimization, self-efficacy, and previous victimization are discussed in relation to predicting this step of the bystander intervention model. Contextual factors that predict accepting responsibility for intervening and taking action, including social norms, peer relationships and status, and teacher-student relationships and school climate, are also detailed.