The use of the National Incident Management System (NIMS) and its associated Incident Command Structure (ICS) structure is relatively new to public health. This was evident in the exercises, in that nearly all health departments had difficulties deciding if and when to implement the ICS process and in identifying the party who would serve as incident commander. Similar challenges were seen in the decision and processes related to opening an Emergency Operations Center (EOC). As a result, in many exercises, local public health officials delayed taking these steps and preferred maintaining a more informal management process. This approach was preferred even as the outbreak became progressively larger, thereby stressing these informal networks.