Zeta Psi (ΖΨ) is one of the world's oldest collegiate fraternities. Its members are known as "Zetes" (IPA: zeɪts).
Zeta Psi was founded on June 1, 1847 at New York University. The organization now comprises fifty-three active chapters and thirty-four inactive chapters, encompassing roughly fifty thousand brothers, and is a founding member of the North American Interfraternity Conference. It has historically been selective about the campuses at which it has established chapters, focusing on forging new territory and maintaining a presence at prestigious institutions: it was the first fraternity on the West Coast at the University of California, Berkeley, on June 10, 1870, the first fraternity in Canada at the University of Toronto, March 27, 1879, and the only fraternity to have chapters simultaneously at all eight Ivy League schools with the chartering of the Eta chapter at Yale University in 1889 (though this claim lasted only a few years, owing to faculty opposition to the Princeton University chapter). The fraternity became intercontinental on May 3, 2008 with the chartering of Iota Omicron at the University of Oxford, and then with the chartering of Theta Omicron at Trinity College Dublin in 2012. Its newest such chapter, Psi Omicron at the University of Paris, officially joined on May 18, 2019.
The public motto is "ΤΚΦ" (or occasionally as "TKP" when rendered in English).Zeta Psi's international headquarters is located in Pearl River, New York.