The National Incident Management System (NIMS) was developed by the Department of Homeland Security in 2004. The NIMS enables responders at all jurisdictional levels and across all disciplines to work together more effectively and efficiently. It represents a core set of doctrine, principles, terminology, and organizational processes. The incident command system (ICS), conceived over 30 years ago as a standard, on-scene, all-hazards incident management system used for firefighters, hazardous materials teams, rescuers, and emergency medical teams, was incorporated into the NIMS. It was incorporated as the standardized incident organizational structure for the management of all incidents. NIMS and ICS are seen as critical pieces of the incident management system. The NIMS and ICS allow for responding agencies to work together, but only if the foundation has been laid at the local level. The NIMS Integration Center is working toward a common understanding and application of the ICS. This article is intended to provide a historical perspective on the development of ICS, explain how NIMS ICS works, describe how it is different from previous systems, and discuss the future of NIMS ICS training.