Simulation exercises have gained increasing prominence in humanitarian preparedness over the past several years, particularly by the organisations comprising the Inter-Agency Standing Committee (IASC). Simulations serve to test plans, rehearse procedures, identify gaps, solve problems, increase confidence and generally add to the overall capacity of organisations and individuals to react to emergencies in an effective, timely and reliable manner. In any life-saving profession--pilots, fire-fighters, para-medics—drills and practice are required to achieve the best results. The IASC Sub-Working Group on Preparedness, co-chaired by UNICEF and WFP, feels strongly that simulation exercises are vital to improve the quality of humanitarian action. Accordingly, this guide aims to put at the disposal of Government emergency managers an easy-to-use methodology for running simulation exercises in order to enhance their national agencies’ level of preparedness. The guide is intended as a tool for national governments who wish to conduct simple, inexpensive table top and functional exercises to test systems and procedures contained within their national disaster management plans.