The authors employed Latanè and Darley’s model about bystanders’ behavior to explain children’s active defending and passive bystanding behavior in school bullying. The three central steps of the model were operationalized by measuring provictim attitudes, personal responsibility for intervention, and coping strategies. Moreover, the role of perceived expectations from parents and peers was investigated. A total of 759 children and 995 early adolescents participated. The findings from structural equation modeling (SEM) confirmed the hypothesized relationships and the impact of perceived peer and parent pressure on nearly all the study variables. The model was confirmed for both age groups, with only a few differences in the paths’ magnitudes, and the model demonstrated the importance of considering both strictly individual characteristics and contextual variables. These results substantially expand previous findings and have potential interest for both researchers and educators.