Students' role in traditional bullying and cyberbullying was investigated in relation to self-serving cognitive distortions (SSCD), perception of school moral climate and bullying observation. Participants were secondary school students from Spain (n = 568; 286 girls) and the Netherlands (n = 421; 223 girls). The results demonstrated that in both country samples, bullies and bully-victims had higher levels of SSCD. Both Spanish and Dutch students who were directly involved in traditional bullying situations showed more negative perceptions of the school moral climate. In cyberbullying situations, bystanders scored higher on school moral climate perception than bullies and bully-victims. Furthermore, school moral climate perception was negatively associated with traditional bullying observation in the group of victims, and with cyberbullying observation in the case of victims and bystanders. The present findings suggest that future research should focus on the cause-effect relations of these factors, which could include measuring the effects on bullying prevalence of an intervention aimed at SSCD reduction in bullies and bystanders and the improvement of the school moral climate.