This session provides a comprehensive debrief of the Columbine High School shooting, examining the sequence of events, key decisions, and outcomes. Participants will explore both the lessons learned from the incident and the critical lessons that continue to be relevant in today's threat environment. The presentation emphasizes actionable insights for law enforcement, school administrators, first responders, and security professionals, highlighting strategies for preparedness, response, and post-incident management. Through analysis and discussion, attendees will gain a deeper understanding of how past experiences can inform current practices in active shooter response, incident management, and the development of safer school environments.