Delta Upsilon

Delta Upsilon (ΔΥ), commonly known as DU, is a collegiate men's fraternity founded on November 4, 1834, at Williams College in Williamstown, Massachusetts. It is the sixth-oldest, all-male, college Greek-letter organization founded in North America (only Kappa Alpha Society, Sigma Phi, Delta Phi, Alpha Delta Phi, and Psi Upsilon predate). It is popularly and informally known as "DU" or "Delta U" and its members are called "DUs". Although historically found on the campuses of small New England private universities, Delta Upsilon currently has 76 chapters/colonies across the United States and Canada. A number of its buildings are listed on the National Register of Historic Places.

In 2013, Business Insider named Delta Upsilon one of the "17 Fraternities with Top Wall Street Alumni". Notable members include President of the United States James A. Garfield, president of Colombia Juan Manuel Santos, Canadian prime minister Lester B. Pearson, Linus Pauling, Joseph P. Kennedy, Lou Holtz, Kurt Vonnegut Jr., Charles Evans Hughes, Les Aspin, and others. Forty-two brothers of the fraternity have sat in the United States Congress, three in the Parliament of Canada, one in the Imperial House of Peers of Japan, and six on the Queen's Privy Council for Canada. Its members have received six Nobel Prizes, five Olympic gold medals, one Pulitzer Prize, four Medals of Honor, one Lenin Peace Prize, one Presidential Medal of Freedom, seven investitures into the Order of Canada, and one investiture each into the Order of St Michael and St George, the Order of Merit, and the Royal Norwegian Order of St. Olav.

In 2018, the fraternity adopted policies to reduce risk. As of August 1, 2018, hard alcohol was banned from all chapter houses. As of August 1, 2020, chapter houses must be "substance free" (including wine, beer, and drugs), except for chapters that obtained waivers through 2022, based upon good behavior.