George C. Marshall Institute

The George C. Marshall Institute (GMI) is an American politically conservative think tank established in 1984 in Washington, D.C. with a focus on scientific issues and public policy. In the 1980s, the Institute was engaged primarily in lobbying in support of the Strategic Defense Initiative. Since the late 1980s, the Institute has put forward environmental skepticism views, and in particular has disputed mainstream scientific opinion on climate change, although it continues to be active on defense policy. The George C. Marshall Institute has been described by Newsweek as a "central cog in the denial machine." The institute is named after the World War II military leader and statesman George C. Marshall, whose own political beliefs were diametrically opposed to those the institute advocates.

Historian Naomi Oreskes states that the institute has, in order to resist and delay regulation, lobbied politically to create a false public perception of scientific uncertainty over the negative effects of second-hand smoke, the carcinogenic nature of tobacco smoking, the existence of acid rain, and on the evidence between CFCs and ozone depletion.