fraternity and sorority, in American colleges, a student society formed for social purposes, into which members are initiated by invitation and occasionally by a period of trial known as hazing. Fraternities are usually named by two or three Greek letters and are also known as Greek-letter societies; women's Greek-letter societies are commonly called sororities. The oldest Greek-letter society is Phi Beta Kappa, founded (1776) at the College of William and Mary, Williamsburg, Va. It soon became a scholarship honor society. After 1830 the literary societies that existed in many colleges were slowly supplanted by fraternities modeled on the three established (1825–27) at Union College. After 1870 many professional and honorary fraternities were established to give recognition to scholarship in various fields. Most fraternities and sororities, however, serve mainly as social clubs. The typical Greek-letter society owns or rents a house that is used as a residence hall for members and as a center for social activities. Some Greek-letter societies have only one local organization or chapter; others are nationally organized with chapters in several institutions. The Interfraternity Conference (1909) and the National Panhellenic Congress (1929) were established to consult on the common interests of American fraternities and sororities. Because many fraternities only admit new members on the basis of a unanimous vote, many of the organizations have been able to maintain discriminatory entrance policies. For this reason, and because of incidents of violent or abusive hazing, fraternities are forbidden on some campuses and their activities severely curtailed on many others.

See W. R. Baird, Manual of American College Fraternities (rev. ed. 1949); W. A. Scott, Values and Organizations: A Study of Fraternities and Sororities (1965).