The term Triads is used to designate certain historic groupings of seminal college fraternities

Fraternities and sororities

Fraternities and sororities are fraternal social organizations for undergraduate students. In Latin, the term refers mainly to such organizations at colleges and universities in the United States, although it is also applied to analogous European groups also known as corporations...

 in North America.

Union Triad

The Union Triad is a group of three early fraternities founded at Union College

Union College

Union College is a private, non-denominational liberal arts college located in Schenectady, New York, United States. Founded in 1795, it was the first institution of higher learning chartered by the New York State Board of Regents. In the 19th century, it became the "Mother of Fraternities", as...

 in Schenectady, New York

Schenectady, New York

Schenectady is a city in Schenectady County, New York, United States, of which it is the county seat. As of the 2010 census, the city had a population of 66,135...

: the Kappa Alpha Society

Kappa Alpha Society

The Kappa Alpha Society , founded in 1825, was the progenitor of the modern fraternity system in North America. It was the first of the fraternities which would eventually become known as the Union Triad...

 (established 1825), Sigma Phi

Sigma Phi

The Sigma Phi Society was founded on 4 March 1827, on the campus of Union College as a part of the Union Triad in Schenectady, New York.It is the second oldest Greek fraternal organization in the United States, and the oldest in continuous existence...

 (1827) and Delta Phi

Delta Phi

Delta Phi is a fraternity founded in 1827 at Union College in Schenectady, New York. Founded as part of the Union Triad, along with the Kappa Alpha Society and Sigma Phi Society, Delta Phi was the third and last member of the Triad...

 (1827). No formal organization exists.

These three organizations are the oldest continuously existing Greek-letter social fraternities in North America.

Other fraternities which owe their birth to Union College include Psi Upsilon

Psi Upsilon

Psi Upsilon is the fifth oldest college fraternity in the United States, founded at Union College in 1833. It has chapters at colleges and universities throughout North America. For most of its history, Psi Upsilon, like most social fraternities, limited its membership to men only...

 (1833), Chi Psi

Chi Psi

Chi Psi Fraternity is a fraternity and secret society consisting of 29 active chapters at American colleges and universities. It was founded on Thursday May 20, 1841, by 10 students at Union College with the idea of emphasizing the fraternal and social principles of a brotherhood...

 (1841) and Theta Delta Chi

Theta Delta Chi

Theta Delta Chi is a social fraternity that was founded in 1847 at Union College. While nicknames differ from institution to institution, the most common nicknames for the fraternity are Theta Delt, Thete, TDX, and TDC. Theta Delta Chi brothers refer to their local organization as Charges rather...

 (1847). Collectively, these many foundings earned Union College the title Mother of Fraternities

Mother of Fraternities

The Mother of Fraternities is a term commonly used to refer to two colleges: Union College and Miami University.Union College was the site in which three fraternities in the United States, Kappa Alpha Society, Sigma Phi, and Delta Phi, known collectively as the Union Triad, were founded between...

.

Miami Triad

The Miami Triad refers to three fraternities founded at Miami University

Miami University

Miami University is a coeducational public research university located in Oxford, Ohio, United States. Founded in 1809, it is the 10th oldest public university in the United States and the second oldest university in Ohio, founded four years after Ohio University. In its 2012 edition, U.S...

 in Oxford, Ohio

Oxford, Ohio

Oxford is a city in northwestern Butler County, Ohio, United States, in the southwestern portion of the state. It lies in Oxford Township, originally called the College Township. The population was 21,943 at the 2000 census. This college town was founded as a home for Miami University. Oxford...

 in the 19th century: Beta Theta Pi

Beta Theta Pi

Beta Theta Pi , often just called Beta, is a social collegiate fraternity that was founded in 1839 at Miami University in Oxford, Ohio, USA, where it is part of the Miami Triad which includes Phi Delta Theta and Sigma Chi. It has over 138 active chapters and colonies in the United States and Canada...

 (1839), Phi Delta Theta

Phi Delta Theta

Phi Delta Theta , also known as Phi Delt, is an international fraternity founded at Miami University in 1848 and headquartered in Oxford, Ohio. Phi Delta Theta, Beta Theta Pi, and Sigma Chi form the Miami Triad. The fraternity has about 169 active chapters and colonies in over 43 U.S...

 (1848), and Sigma Chi

Sigma Chi

Sigma Chi is the largest and one of the oldest college Greek-letter secret and social fraternities in North America with 244 active chapters and more than . Sigma Chi was founded on June 28, 1855 at Miami University in Oxford, Ohio when members split from Delta Kappa Epsilon...

 (1855). Historians of fraternities often compare the significance of the Miami Triad to that of the earlier Union Triad.

Delta Zeta

Delta Zeta

Delta Zeta is an international college sorority founded on October 24, 1902, at Miami University in Oxford, Ohio. Today, Delta Zeta has 158 collegiate chapters in the United States and over 200 alumnae chapters in the United States, the United Kingdom, and Canada...

 sorority was founded at Miami University in 1902, and Phi Kappa Tau

Phi Kappa Tau

Phi Kappa Tau is a U.S. national collegiate fraternity.-History:Phi Kappa Tau Fraternity was founded in the Union Literary Society Hall of Miami University's Old Main Building in Oxford, Ohio on March 17, 1906...

 fraternity in 1906. Delta Sigma Epsilon

Delta Sigma Epsilon

Delta Sigma Epsilon was a national collegiate social sorority operating in the United States from 1914 to 1956. It was absorbed by Delta Zeta sorority.-History:...

 sorority began there in 1914, merging in 1956 with Delta Zeta. These numerous Greek organization foundings cause some to refer to the school also as the Mother of Fraternities

Mother of Fraternities

The Mother of Fraternities is a term commonly used to refer to two colleges: Union College and Miami University.Union College was the site in which three fraternities in the United States, Kappa Alpha Society, Sigma Phi, and Delta Phi, known collectively as the Union Triad, were founded between...

.

It has been tradition at some campuses that have chapters of each of the Miami Triad, such as the University of Kansas

University of Kansas

The University of Kansas is a public research university and the largest university in the state of Kansas. KU campuses are located in Lawrence, Wichita, Overland Park, and Kansas City, Kansas with the main campus being located in Lawrence on Mount Oread, the highest point in Lawrence. The...

, and the University of Mississippi

University of Mississippi

The University of Mississippi, also known as Ole Miss, is a public, coeducational research university located in Oxford, Mississippi. Founded in 1844, the school is composed of the main campus in Oxford, four branch campuses located in Booneville, Grenada, Tupelo, and Southaven as well as the...

, to hold an annual party, formal, or ball, often referred to as "Miami Triad" or simply "Triad", to commemorate their tie to each other and the Miami Triad's place in Greek history. This tradition has waned in recent years and some schools have transformed the celebration into new events, such as the University of Kansas' Miami Triad Concert.

Lexington Triad

The Lexington Triad is a group of three fraternities founded by students from colleges in Lexington, Virginia

Lexington, Virginia

Lexington is an independent city within the confines of Rockbridge County in the Commonwealth of Virginia. The population was 7,042 in 2010. Lexington is about 55 minutes east of the West Virginia border and is about 50 miles north of Roanoke, Virginia. It was first settled in 1777.It is home to...

 during Reconstruction following the American Civil War

American Civil War

The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...

.

Members of the triad include Alpha Tau Omega

Alpha Tau Omega

Alpha Tau Omega is a secret American leadership and social fraternity.The Fraternity has more than 250 active and inactive chapters, more than 200,000 initiates, and over 7,000 active undergraduate members. The 200,000th member was initiated in early 2009...

 (founded in Richmond, Virginia

Richmond, Virginia

Richmond is the capital of the Commonwealth of Virginia, in the United States. It is an independent city and not part of any county. Richmond is the center of the Richmond Metropolitan Statistical Area and the Greater Richmond area...

 in 1865 by students from Virginia Military Institute

Virginia Military Institute

The Virginia Military Institute , located in Lexington, Virginia, is the oldest state-supported military college and one of six senior military colleges in the United States. Unlike any other military college in the United States—and in keeping with its founding principles—all VMI students are...

 (VMI) in Lexington), Kappa Alpha Order

Kappa Alpha Order

Kappa Alpha Order is a social fraternity and fraternal order. Kappa Alpha Order has 124 active chapters, 3 provisional chapters, and 2 commissions...

 (founded in 1865 at Washington and Lee University

Washington and Lee University

Washington and Lee University is a private liberal arts college in Lexington, Virginia, United States.The classical school from which Washington and Lee descended was established in 1749 as Augusta Academy, about north of its present location. In 1776 it was renamed Liberty Hall in a burst of...

, and not to be confused with the Kappa Alpha Society

Kappa Alpha Society

The Kappa Alpha Society , founded in 1825, was the progenitor of the modern fraternity system in North America. It was the first of the fraternities which would eventually become known as the Union Triad...

, America's first fraternity, founded at Union College

Union College

Union College is a private, non-denominational liberal arts college located in Schenectady, New York, United States. Founded in 1795, it was the first institution of higher learning chartered by the New York State Board of Regents. In the 19th century, it became the "Mother of Fraternities", as...

 in 1825), and Sigma Nu

Sigma Nu

Sigma Nu is an undergraduate, college fraternity with chapters in the United States, Canada and the United Kingdom. Sigma Nu was founded in 1869 by three cadets at the Virginia Military Institute in Lexington, Virginia...

 (founded in 1869 at VMI). The national headquarters of both the Kappa Alpha Order and Sigma Nu are located in Lexington.

The members of the Triad are sometimes also grouped as part of the Virginia Circle, which includes several other fraternities founded in Virginia roughly during the period of the Lexington Triad: Kappa Sigma

Kappa Sigma

Kappa Sigma , commonly nicknamed Kappa Sig, is an international fraternity with currently 282 active chapters and colonies in North America. Kappa Sigma has initiated more than 240,000 men on college campuses throughout the United States and Canada. Today, the Fraternity has over 175,000 living...

 and Pi Kappa Alpha

Pi Kappa Alpha

Pi Kappa Alpha is a Greek social fraternity with over 230 chapters and colonies and over 250,000 lifetime initiates in the United States and Canada.-History:...

 at the University of Virginia

University of Virginia

The University of Virginia is a public research university located in Charlottesville, Virginia, United States, founded by Thomas Jefferson...

, and sometimes Sigma Phi Epsilon

Sigma Phi Epsilon

Sigma Phi Epsilon , commonly nicknamed SigEp or SPE, is a social college fraternity for male college students in the United States. It was founded on November 1, 1901, at Richmond College , and its national headquarters remains in Richmond, Virginia. It was founded on three principles: Virtue,...

 at Richmond College

University of Richmond

The University of Richmond is a selective, private, nonsectarian, liberal arts university located on the border of the city of Richmond and Henrico County, Virginia. The University of Richmond is a primarily undergraduate, residential university with approximately 4,000 undergraduate and graduate...

.

Jefferson Duo

The Jefferson Duo includes the fraternities Phi Gamma Delta

Phi Gamma Delta

The international fraternity of Phi Gamma Delta is a collegiate social fraternity with 120 chapters and 18 colonies across the United States and Canada. It was founded at Jefferson College, Pennsylvania, in 1848, and its headquarters are located in Lexington, Kentucky, USA...

 and Phi Kappa Psi

Phi Kappa Psi

Phi Kappa Psi is an American collegiate social fraternity founded at Jefferson College in Canonsburg, Pennsylvania on February 19, 1852. There are over a hundred chapters and colonies at accredited four year colleges and universities throughout the United States. More than 112,000 men have been...

, founded in 1848 and 1852, respectively, at Jefferson College in Canonsburg, Pennsylvania

Pennsylvania

The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

. A third, Kappa Phi Lambda

Kappa Phi Lambda (fraternity)

Kappa Phi Lambda was an American collegiate fraternity. It was founded on February 19, 1862 at Jefferson College in Canonsburg, Pennsylvania...

, was also founded there but dissolved in 1874. In 1865, Jefferson College combined with Washington College to become Washington and Jefferson College.