This research investigated the role of individual and situational characteristics involved in motivating active cyber-defending online. Undergraduate students (N = 278, Mage = 19.10) were given questionnaires examining online bystander behaviour, moral disengagement, empathy, self-efficacy, social power, their relationship to the victim, the psychosocial cost of defending, and demographic questions. Three hypotheses were investigated. First, individuals low on moral disengagement, high on empathy, defender self-efficacy, social power, know the victim, and do not expect there to be a high psychosocial cost for defending will help the victim. Second, it was hypothesized that people who are low on moral disengagement, high on empathy, low on defender self-efficacy, social power, do not know the victim, and expect a high psychosocial cost will be less likely to defend, acting as passive cyber bystanders.Third, reinforcing the cyber-bully online was expected to be associated with high moral disengagement, low empathy, defender self-efficacy, high social power, not knowing the victim, and not expecting a high psychosocial cost to defend. Active cyber defending was related to high defender self-efficacy, whereas low defender self-efficacy, popularity, and high moral disengagement predicted remaining passive online. Conversely, reinforcing the cyber-bully online was predicted by high moral disengagement and low empathy. These results have implications for furthering our understanding of cyber-defending online and can inform the development of intervention and prevention programs aimed at promoting active defending online.