The school collegial climate presents an important context for teacher professional activities. This study investigated whether teachers' perceptions of school collegial climate characteristics (teacher-leadership collaboration, teacher-teacher collaboration, and teacher-teacher communication) are associated with teachers' active responses to bullying. Four active responses (authority-based interventions, encouraging victim assertiveness, working with the bully, and enlisting other adults) were differentiated, and the effects of teacher characteristics (gender, teaching experience, empathy, and social self-efficacy) were controlled for. The sample comprised 740 teachers from 118 schools in the Czech Republic. The results of multilevel models revealed no significant effects of teacher-leadership collaboration. Individual-level perceptions of teacher-teacher collaboration were positively associated with authority-based interventions and school-level perceptions of teacher-teacher communication were positively associated with working with the bully. The findings suggest that efforts to promote teachers' active responses to bullying could include fostering collaboration and communication among teachers in the school.