The call for a more holistic approach to cope with school violence motivated the present study. The present model postulates that effective teamwork at the school management team level can have a positive impact on the level of school violence. Specifically, the model examined the mediating role of school management team effectiveness (in-role performance and innovation) in the relationship between the organizational-level factors of principals' internal and external boundary activities and school violence. Data was collected from a survey of 692 school members and 92 principals in Israel. The structural equation model confirmed the main hypotheses and indicated that school management team effectiveness fully mediated the relationship of principals' internal boundary activities to school violence. These results carry important practical implications for policymakers to help schools manage school violence issues. Understanding how the principals' boundary activities can enhance school management team effectiveness by facilitating improved knowledge exchange and social relationships is important and may provide a mechanism to decrease school violence. The implications of these findings for both theory and practice are discussed.