The U.S. Department of Energy (DOE) is one of the most interesting and diverse agencies in the federal government. Activated on October 1, 1977, the twelfth cabinet-level department brought together for the first time within one agency two programmatic traditions that had long coexisted within the federal establishment: 1) defense responsibilities that included the design, construction, and testing of nuclear weapons dating from the Manhattan Project effort to build the atomic bomb during World War II and 2) a loosely knit amalgamation of energy-related programs scattered throughout the federal government.

The intent of the DOE History Timeline is to provide the public with easy access to accurate information about the history of DOE and its predecessor agencies. The timeline includes links to reports, speeches, press releases, and other documentation

For background, see A Brief History of the Department of Energy and The Institutional Origins of the Department of Energy.