Despite the fact that schools remain incredibly safe spaces for children and youth to spend time, the occurrence of mass school shootings, although rare, is a pressing issue for our society. In this paper we discuss the importance of action, advocacy, and research related to mass school shootings. Specifically, we discuss research-based actions for preventing and responding to mass school shootings, including multi-tiered systems of support, positive behavior interventions and supports, threat assessment, and trauma-informed care. In regard to advocacy, we focus on the need to discontinue ineffective and, in some cases, harmful practices such as zero-tolerance policies. We conclude with an examination of the needed research in this area, with special attention on the use of active shooter drills and firearm legislation.