Preventing and reducing bullying requires long-term and systematic school-wide actions. Researchers on bullying have given little attention to the school organization and its influence on the ability to implement the necessary actions to prevent and stop bullying. This study examines the relationship between aspects of a school's professional culture and rates of bullying. From a sample of 18,767 students and 1,932 teachers in 85 primary, secondary, and combined schools, subgroups of schools with high (11 schools) and low (10 schools) rates of bullying were identified. Schools with high and low rates differed significantly on all organizational factors; teachers in schools with high rates of bullying reported weaker leadership, teacher affiliation, and collaborative activity than teachers at schools with low rates of bullying. Teacher authority had a mediating role between aspects of the professional culture and rates of bullying. Implications for practice are also discussed.