The Military Police Corps' active shooter preparedness plan is inadequate because several updated tactics, techniques, and procedures that have been developed over the past 20 years and implemented by civilian law enforcement agencies have not been incorporated, leaving the Corps less prepared during active shooter events. The purpose of this phenomenological study was to examine how Military Police Corps leaders trained their law enforcement and support personnel to respond to an active shooter event. The institutional analysis and development framework was used to analyze the day-to-day operational decisions within the Military Police Corps. Data for the qualitative case study were collected through semi structured interviews with 15 Military Police Corps leaders and soldiers across 5 military police battalions in the United States and Europe and military police training records. These data were subjected to axial and open coding, followed by a thematic analysis procedure. Participants perceived that the Corps' active shooter preparedness training hours and methodology are insufficient to maintain proficiency in active shooter preparedness, that dispatchers are not properly trained on receiving active shooter calls, and that live exercise training for first responders is inadequate. Recommendations for Military Police Corps leadership include updating the training methodology for first responders and dispatchers, providing better tactical equipment for first responders, and revising policies in order to improve the Military Police Corps' active shooter preparedness program. Implementation of these recommendations may promote public safety.