This study examined whether the degree to which bullying is normative in the classroom would moderate associations between intra- (cognitive and affective empathy, self-efficacy beliefs) and interpersonal (popularity) factors and defending behavior. Participants were 6,708 third- to fifth-grade children (49% boys; M-age = 11 years) from 383 classrooms. Multilevel modeling analyses revealed that children were more likely to defend in response to their affective empathy in classrooms with high levels of bullying. In addition, popular students were more likely to support victims in classrooms where bullying was associated with social costs. These findings highlight the importance of considering interactions among individual and contextual influences when trying to understand which factors facilitate versus inhibit children's inclinations to defend others.