St. Anthony Hall or the Fraternity of Delta Psi is an American fraternity and literary society. Its first chapter was founded at Columbia University on January 17, 1847, the feast day of Saint Anthony the Great. The fraternity is a non–religious, nonsectarian organization. In 1879, William Raimond Baird's American College Fraternities characterized the fraternity as having "the reputation of being the most secret of all the college societies." A 2015 writer for Vanity Fair says the fraternity is "a cross between Skull and Bones and a Princeton eating club, with a large heaping of Society and more than a dash of Animal House." Nearly all chapters of St. Anthony Hall are coed.

References to St. Anthony Hall have appeared in the works of F. Scott Fitzgerald, John O'Hara, and Tom Wolfe.

According to Baird's Manual, the Alpha chapter of the Fraternity of Delta Psi was founded at Columbia University on January 17, 1847 by John Hone Anthon, Sam. F. Barger, Charles Arms Budd, and William Myn Van Wagener. In The Review magazine, the fraternity says Anthon was a founder and the first leader of the fraternity. (He would later serve as grand master, i.e. president, of Freemasons in New York, for the term 1870-71.) Another source says Delta Psi was started by the fifteen-year-old Edward Forbes Travis who came to Columbia University from England "with an odd fascination for St. Anthony the Great, the gnarled fourth-century mystic." In this scenario, Travis shared "certain rituals" with a Charles Arms Budd on the saint's feast day, creating "a sacred bond that was soon extended to others."

According to its national website, Delta Psi was founded on the feast day of Saint Anthony the Great as a "fraternity dedicated to the love of education and the well-being of its members." It is a non–religious, nonsectarian organization. The fraternity developed "a literary flavor: members would spend hours reading essays to one another for general critique or amusement." By 1853, it was holding an Annual Literary Festival and Dinner. It also held evenings featuring orators and poets, often publishing the poems or speeches.

A Beta chapter was formed at New York University on January 17, 1847. However Beta was short-lived; the Columbia College's Record lists the New York University founders alongside its students. In 1879, Baird's listed seventeen chapters opening throughout the Northeast and South during the mid-19th-century.

During the Civil War, formal contact ended between the Northern and Southern chapters, and all of the Southern chapters closed. In fact, 25% of the fraternity's membership died in the Civil War, with 90 of the 109 deaths coming from the Southern chapters. In December 1865, the fraternity held its annual convention in New York City. The New York Times reported, "Attendance from all the Northern chapters was large, and measures were taken to give the most cordial assistance in response to applications for the rehabilitation of the Southern chapters in such of their colleges are again in operation."

Three of the Southern chapters resumed operations: the University of Virginia, the University of Mississippi, and Washington and Lee. In April 1867, eleven members of the Williams College chapter commissioned a life-sized portrait of a fallen brother; the portrait was displayed at the Schwabe Gallery of Fallen Heroes in Boston, along with the portraits of four other Delta Psi brothers. Members from many Southern chapters attended a commemorative dinner in New York City in December 1871.

In 1894, Yale's Sigma chapter built a dormitory and named it St. Anthony Hall, apparently the first use of that name. The Fraternity of Delta Psi also became known as the Order of St. Anthony and St. Anthony Hall.