Simulation is perhaps the most widely used method for training emergency management workers. Despite its wide application, traditional simulation suffers from several constraints and limitations, which motivate us to pursue a different way - virtual simulation, as an alternative and supplement for the traditional training method. Utilization of groupware, network, and other information technologies makes virtual simulation more flexible and easier to prepare. Although virtual simulation can overcome some of the constraints related to physical simulation, so far there are little evidences that this new method can achieve similar or even better training effects compared with traditional simulation training method. To test the effects of this new training approach and the methodology to run it, several pilot trials have been conducted in the U.S. and Europe. This article is an exploratory study of a pilot emergency preparedness planning virtual simulation conducted in NJIT in late 2004. This study will help us understand the nature of virtual simulation, and help us improve the theories and designs of virtual simulation for emergency preparedness.