Abstract Gas hydrate has been a target of research by the U.S. Department of Energy (DOE) for more than two decades. Since 2000, an accelerated DOE research and development effort has included efforts to improve the understanding of gas-hydrate occurrence, its behavior under dynamic conditions, and its potential as a future energy source. The DOE has supported several important accomplishments: improved the understanding of the fundamental physical and chemical properties of gas hydrate and gas-hydrate-bearing sediments; significant strides in understanding how to detect and characterize gas-hydrate accumulations; improved understanding of the complexity of gas hydrate in nature; development of new tools to sample, measure, and monitor gas hydrate in the field; and the development of the first reservoir models of gas hydrates. Ongoing work is expanding and extending these accomplishments within five broad categories: laboratory studies, modeling, exploration technologies, field studies, and field sample collection and analysis tool development. This work is being conducted through several cooperative agreements with universities and industries through funding for specific activities within the DOE National Laboratory system and through interagency agreements with the U.S. Geological Survey and Naval Research Laboratory.