This chapter discusses the history and origins of the Incident Command System, the National Incident Management System (NIMS), and The National Response Plan. The department of homeland security was officially established on January 23, 2003 causing a massive reorganization of the government with the intent of providing a unifying core for a vast national network of institutions and organizations that are important to national security and emergency response. Among the most likely reasons for response failure in an emergency are confusion about who is in charge, unclear lines of authority, and lack of clear communication. The national response plan is constructed around the described NIMS and is intended to be an all-hazards plan that provides the structure for incident management at all levels of federal, state, and local government and for any major type of incident including a major public health emergency. Environmental health professionals must have a large arsenal of skills and knowledge to competently perform their day-to-day activities.