Past research on school bullying focused on the role of the bully, suggesting that this active perpetrator is characterized by low empathy, low self-regulation, and high moral disengagement (MD). Studies recently demonstrated a relationship between dispositional mindfulness and bullying as well. However, in the last 2 decades, research has broadened this perspective, suggesting that active and passive bystanders may play a major role in school bullying by either supporting or opposing bullying. In this research, we examined whether empathy, MD, self-regulation, and mindfulness are significantly associated with probullying, defending, and bystanding behaviors. A total of 429 middle and high school adolescents from Israel (mean age = 16.81 years, SD = 1.62) completed online questionnaires. Through structural equation modeling, we found that empathy was associated with both, self-regulation and defending behaviors. MD was associated with defending and probullying behaviors. Dispositional mindfulness was associated with all three roles we examined. All these relationships were significant and in the expected direction. As mindfulness is a disposition that can be cultivated, this finding may have further implications in programs that aim at reducing school bullying.