Active shooter incidents are becoming more common, and although they are still rare compared with other shooting sites, incidents have increased in health care facilities. Agencies such as the Federal Bureau of Investigation, The Joint Commission, and the Emergency Nurses Association have emphasized that an action plan and training are essential for hospital preparedness.Planning an active shooter simulation for the emergency department was a complex project and involved collaboration between the hospital's Emergency Management team, simulation staff, security, and ED leadership, which included the educators and clinical nurse specialist. Decisions were made related to appropriate location, equipment, and needs for the functional exercises. Scenarios also were developed with roles for the ED population and actors.A total of 204 staff members participated in the simulations between August and December of 2016. A survey was distributed to staff who attended the simulation. Ninety-two percent of staff felt more prepared to respond to an active shooter event and reported a 70% improvement in knowledge and preparation. Attendees reported their first response would be to flee the scene (66%), protect patients (15%), hide (7%), fight (6%), and call 911 (4%).The active shooter education included a didactic portion, a pre- and postsurvey, and the simulation event. The presentation focused on statistics of active shooters, possible threats, and the concepts of RUN, HIDE, and FIGHT. A Critical Incident Stress Management team member was present to ensure the emotional and psychological health of the participants. The debriefing was a crucial part of the simulation experience so staff could talk about their experience and express their concerns.