The Heritage Foundation, sometimes referred to simply as Heritage, is an activist American conservative think tank based in Washington, D.C. Founded in 1973, it took a leading role in the conservative movement in the 1980s during the presidency of Ronald Reagan, whose policies were taken from Heritage Foundation studies, including its Mandate for Leadership.

A think tank, or policy institute, is a research institute that performs research and advocacy concerning topics such as social policy, political strategy, economics, military, technology, and culture. Most think tanks are non-governmental organizations, but some are semi-autonomous agencies within government, and some are associated with particular political parties, businesses or the military. Think tanks are often funded by individual donations, with many also accepting government grants.