What is an EOC?
An Emergency Operations Center-EOC is a concept , designated location, and a function which “…brings together essential personnel involved in overseeing the response to and mitigation of [an] emergency”. 
EOCs differ from the Incident Command System-ICS. ICS can be considered the ‘on the ground’ leadership, management, and control of an emergency incident. Whereas, the EOC is a coordinating entity (not a command entity).
What does an EOC do?
The primary function of an EOC is to coordinate resources in support of field operations, be an interface point for external agencies, organizations, and communicate information to the public. For the EOC to exist, there must be a reason to use it, a chief administrative officer or designated emergency manager to lead it, and an equipped facility designed to function as a central hub. An EOC is only needed when the agencies managing an incident run out of resources. 
The EOC provides critical support functions (ESFs ) at a designated physical location (although it may and can be a VEOC-Virtual Emergency Operations Center) . Those functions, by FEMA designation are:
- ESF #1 – Transportation
- ESF #2 – Communications
- ESF #3 – Public Works and Engineering
- ESF #4 – Firefighting
- ESF #5 – Emergency Management
- ESF #6 – Mass Care, Emergency Assistance, Housing, and Human Services
- ESF #7 – Logistics Management and Resource Support
- ESF #8 – Public Health and Medical Services
- ESF #9 – Search and Rescue
- ESF #10 – Oil and Hazardous Materials Response
- ESF #11 – Agriculture and Natural Resources
- ESF #12 – Energy
- ESF #13 – Public Safety and Security
- ESF #14 – Long-Term Community Recovery
- ESF #15 – External Affairs 
How is the EOC organized and managed?
During a disaster, the EOC gathers, processes, and shares information, manages resources, and brings together policy makers in a coordinated fashion. FEMA offers guidance on four typical ways of organizing an EOC..
- Major Management Activities
- ICS Structure
- ESF Structure
- MAC Group Structure 
Each EOC may be managed in a slightly different manner depending upon agreed to guiding principles, FEMA guidance through the national response framework, and available resources. For example, the State of North Carolina uses the following structure:
- Command and Control
- Finance 
What roles are necessary for a successful EOC?
The Chief Administrator (CAO or CEO) of a jurisdiction is may and often calls on the individual responsible for the Office of Emergency Management in the affected area. This person may be the actively operating ‘leader’ of the EOC, while essentially reporting to the CAO.
The type of structure will dictate some of the roles to be filled including:
- Policy Group – chief elected official
- Resource Group – representatives from participating agencies
- Operations Group – law, fire, public works, EMS and others
- Coordination Group – GIS, assessment analyst 
 Larson, Randall, 2006. “EOCs for the 21st Century”, Homeland1 News. Source accessed 2-6-10: http://www.homeland1.com/homeland-security-columnists/randall-larson/articles/350122-eocs-for-the-21st-century/
 Lindell, Michael K., Prater, Carla, Perry, Ronald W. 2007. “Introduction to Emergency Management”, Chapter 10, pgs. 327-330.
 FEMA. 2010. “Emergency Support Function Annexes“. Source accessed 2-7-10: http://www.fema.gov/pdf/emergency/nrf/nrf-esf-intro.pdf
 Stephen Davis. (2002). Virtual Emergency Operations Centers. Risk Management Magazine, 49(7), 6 pp. Source accessed on 2-6-10: http://proquest.umi.com.library.norwich.edu/pqdweb?did=132744341&VName=PQD&clientId=55007&sid=1&Fmt=3&RQT=309&cfc=1
 FEMA. 2010. “IS-775 EOC Management and Operations – Lesson 3: EOC Staffing and Organization“. Source accessed 2-7-10: http://training.fema.gov/EMILMS/IS775/EOC0103000.htm
 NC Division of Emergency Management, 2007. “Emergency Operations Center – Standard Operating Guide”. Source accessed 2-7-10: http://www.dem.dcc.state.nc.us/ARCHIVES/EOC-SOG.pdf