Bystanders play a crucial role in aggressive behavior in group contexts. Cyberbystanders can react in proactive ways such as assisting a cyberbully or defending the victim. Since school relationships spill over to the online world, the school context is likely to influence students' online behavior. In the present study, we examine the influence of school climate on active cyberbystanding behavior beyond the influence of individual social competences. Participants were 726 students from a more comprehensive study, who were classified as non-victims and non-bullies (i.e., pure bystanders). They were from 36 classes in five schools in Germany (Grades 7-10; M[subscript age] = 13.37 years, SD[subscript age] = 1.01 years, 53.3% female). Two hypothetical scenarios were used to operationalize active bystanding: one for assisting in cyberbullying and one for defending the cybervictim. Separate multilevel analyses were conducted to predict assisting in cyberbullying and defending the victim on the individual level, respectively. Individual-level independent variables were affective and cognitive empathy. Class-level independent variables were assessed with six subscales of the Inventory of School Climate (ISC-S; Brand et al. 2003). Age, gender, class-level offline and online bullying, and offline and online victimization were controlled for. Results showed cognitive and affective empathy, lack of positive peer interactions, and offline bullying to predict assisting. Defending was predicted by cognitive and affective empathy, lack of safety problems, and teacher support. School plays a role in students' online bystander behavior and interventions should aim to foster a supportive school climate.