"Real-time citizen interaction has the potential to transform society's response to crisis situations. New systems and processes must be developed to support citizen involvement and first responders must be trained in their use. The Citizens' Emergency Response Portal System (CERPS) Simulation Experiment (CERPS SIMEX) evaluated examined the role of public interaction through social media during emergency situations. The SIMEX was conducted over five days in October 2012 at the Net-Centric C4ISR Experimentation Lab (NCEL) housed at The MITRE Corporation's McLean, Va., headquarters and on the George Mason University (GMU) campus in Fairfax, Va. No actual emergency activities occurred on the campus; the SIMEX was conducted behind a firewall to avoid unintentional public panic. The SIMEX brought together emergency response personnel from federal, state, county and city jurisdictions in the National Capital Region of Washington, D.C. Emergency operators used real command and control systems with simulated reporting and sensor systems. Citizen participants were volunteers recruited from the GMU student body. The primary purpose of the SIMEX was to examine the hypothesis that citizen participation via social media in crisis response decision-making can improve the outcome of a crisis. This SIMEX was intended to establish a baseline for future research on crisis response decision support employing citizen participation."