Introduction: BACKGOUND In the modern era of terrorism and senseless violence, it is essential that hospital staff have expertise in implementation of a mass casualty incident (MCI) plan. OBJECTIVES 1. To assess current gaps in implementation of an academic urban hospital code orange plan using live simulation and tabletop exercise. 2. To identify and educate front-line staff to champion a hospital-wide MCI plan. INNOVATION Historically, in order to limit resource utilization and impact on patient care, disaster response training of front-line staff involved tabletop exercises only. The tenets of experiential learning suggest that learner engagement through realistic active practice of skills achieves deeper uptake of new knowledge. We enhanced the traditional tabletop approach through novel use of live actor patients presenting to an academic, urban emergency department (ED) during a hospital-wide MCI simulation. Methods: To assess the current code orange plan, an interprofessional, committee comprising expert leaders in trauma, emergency preparedness, emergency medicine and simulation integrated tabletop and live simulation to stage a MCI based on a mock incident at a new subway station. ED staff, the trauma team and champions from medicine, surgery and critical care participated along with support departments such as Patient Flow, Patient Transport, Environmental Services and the Hospital Emergency Operations Centre. Ten live actor patients and eight virtual patients presented to the ED. The exercise occurred in situ in the ED. Other participating departments conducted tabletop exercises and received live actor patients. Results: CURRICULUM Staff decanted the ED and other participating units using their current knowledge of hospital code orange policy. Live and virtual patients were triaged and managed according to severity of injuries. Live actor patients were assessed, intervened and transported to their designated unit. Virtual patients were managed through verbal discussion with the simulation controllers. An ED debrief took place using a plus/delta approach followed by a hospital-wide debrief. Conclusion: CONCLUSION An interprofessional hospital-wide MCI simulation revealed important challenges such as communication, command and control and patient-tracking . The exercise ignited enthusiasm and commitment to longitudinal practice and improvement for identified gaps.