This article is about Radcliffe College, in Cambridge, Massachusetts, United States. There is also a Ratcliffe College, in Leicestershire, United Kingdom.

Radcliffe College is the historical name of a women's educational institution closely associated with Harvard University, one of the Seven Sisters.

The "Harvard Annex" for women's instruction by Harvard faculty was founded in 1879 and chartered as Radcliffe College by the Commonwealth of Massachusetts in 1894. It is named for Lady Ann (Radcliffe) Mowlson, who established the first scholarship at Harvard in 1643. The first president was Elizabeth Cary Agassiz, widow of Harvard professor Louis Agassiz. Radcliffe built its own campus in Cambridge, Massachusetts, not far from that of Harvard.

During World War II, Harvard and Radcliffe signed an agreement which allowed women to attend classes at Harvard for the first time, officially beginning joint instruction in 1943. From 1963, Radcliffe students received Harvard diplomas signed by the presidents of Radcliffe and Harvard, and joint commencement exercises began in 1970. The same year, several Harvard and Radcliffe dormitories began swapping students experimentally, and in 1972 full coresidence was instituted. The schools' departments of athletics merged two years later.

In 1977, Harvard and Radcliffe signed an agreement which put undergraduate women entirely in Harvard College, maintaining for them only a theoretical membership in Radcliffe College. In practice all the energies of Radcliffe (which remained an autonomous institution) were devoted to its other initiatives, such as the Bunting fellowship program. On October 1, 1999, this quaint and unusual arrangement came to an end, as Radcliffe College was finally fully absorbed into Harvard University; female undergraduates were henceforward members only of Harvard College while Radcliffe College evolved into the Radcliffe Institute for Advanced Study.

However, several undergraduate student organizations in Harvard College still refer to Radcliffe in their names. Furthermore, two athletic teams (one varsity, one a student-organized club) still compete under the name of Radcliffe — crew, which still rows with Radcliffe's black-and-white oarblades instead of Harvard's crimson-and-white (in 1976 the team had been the only varsity team which voted not to adopt the Harvard name); and rugby.