The Flat Hat Club is the popular name of a collegiate secret society and honor fraternity founded in 1750 at the College of William & Mary in Williamsburg, Virginia.

[1] Early in the 21st century, the Education section of The New York Times profiled America's oldest university clubs and societies and included a letter, now housed in the archives at Swem Library, which Thomas Jefferson wrote to Thomas McAuley, mentioning Jefferson's membership in the F.H.C.

[3] William & Mary alumnus and third American president Thomas Jefferson may be the most famous member of the Flat Hat Club.

John Heath, a student at William and Mary who in 1776 sought but was refused admission to the P.D.A., later established the first Greek-letter fraternity, the Phi Beta Kappa Society.

suspended the group's activities in 1781, probably due to the suspension of academic exercises at the university as the contending armies of the American Revolution approached Williamsburg during the Yorktown campaign.

"The memory of this fraternity had entirely died out at William and Mary, but [after 1909, there was a] discovery of certain manuscript material in the correspondence of St. George Tucker, who was a student of the College in 1772.

[8] The name of the group was revived in the twentieth century by application to a select group of twelve undergraduate men and four professors which had been founded in 1916 as the Spotswood Club (it thus differed markedly from the original society, a fraternity of six undergraduate men with alumnus members in urbe – that is, "in town", having graduated from the university).

It suspended its activities in 1943 as the number of men enrolled at the College steeply declined because of American involvement in World War II.