Dumbarton Oaks is a nineteenth-century mansion located in the Georgetown section of Washington, DC. It houses the Dumbarton Oaks Research Library and Collection, a leading center for scholarship in Byzantine studies, Pre-Columbian studies and the history of landscape architecture.

The mansion was built in 1800 in the Federal style. It was purchased in 1920 by Robert Woods Bliss (1875-1962), a longtime member of the U.S. Foreign Service, and his wife, Mildred Barnes Bliss (1875-1969), a prominent art collector. Additions to the house have been made by several architects including Phillip Johnson.

Over their lives, Mr. and Mrs. Bliss assembled large and important collections of artifacts and books, which they housed at Dumbarton Oaks. In 1940, they donated their collections together with the house and its grounds to create the Dumbarton Oaks Research Library and Collection, to be managed by the trustees of Harvard University. The institution was originally dedicated solely to Byzantine studies, but the scope was later broadened to include Pre-Columbian studies and the history of landscape architecture.

The libraries of Dumbarton Oaks contain over 100,000 volumes. There are a number of resident scholars; in addition, about forty fellowships are awarded each year for visiting scholars.

There are about ten acres (four hectares) of gardens on the grounds of Dumbarton Oaks, designed by the landscape architect Beatrix Farrand. The gardens are open to the public.

In 1944, Dumbarton Oaks hosted the Dumbarton Oaks Conference, an international meeting that laid the groundwork for the creation of the United Nations.