The Environmental Protection Agency’s involvement in counter-terrorism is one of being part of the National Response System which includes the Federal Bureau of Investigation (FBI) and other local, State, and Federal agencies. A key EPA player in this system is the On-Scene Commander (OSC). This paper presents a brief overview of the OSC’s role in crisis management and how the OSC’s role takes form once an incident has occurred. The general role of the OSC in crisis management entails: providing technical advice to the FBI On-Scene Commander, assisting in the conduct of scientific and technical assessments, making recommendations for the deployment of response assets, and assisting the FBI in working with State and local responders in the ICS/UC. Once a terrorist incident has occurred there are initial actions/steps to be taken under crisis management, as well as consequence management. Issues are addressed concerning the OSC’s interaction with the FBI OSC.