There were three principal founders of Omicron Delta Kappa: J. Carl Fisher, who was Business Manager of the Student Magazine; Rupert Nelson Latture, President of the YMCA; and, William Mosely Brown, Phi Beta Kappa. Together with three faculty members, including the President of the University and the Dean of Engineering, these men gradually selected nine additional men to affiliate with them. When there were fifteen members, the first public announcement of the establishment of Omicron Delta Kappa was made in the student newspaper on January 12, 1915. With the passage of Title IX of the Civil Rights Act, the first woman was elected to ODK in 1973.Prior to that, women were selected for Mortar Board and men for ODK.

The Sigma Circle of ODK was founded on February 2, 1927 by six men who immediately began tapping undergraduate members of ODK. Formerly, men knew that they were being considered for ODK if they were invited to the Calvert Cotillion in December. Their formal initiation would occur at a convocation in the Spring. Many famous people have been initiated into Sigma Circle, some as student and faculty members, others as Honorary members. Some of Sigma Circle's famous members include President Franklin D. Roosevelt, Vice President Alben W. Barkley, the Earl of Halifax, Admiral Stansfield Turner, and Congressman Steny Hoyer.

Sigma Circle is very proud of its long and proud history. It originated the Annual Awards Banquet; awards an annual $1000 scholarship to an incoming freshman who was a high school leader; selects the "Top Ten Freshmen" and the "Sophomore Leader of the Year;" and with the help of alumni donations constructed the ODK Fountain on McKeldin Mall, which was built to create a lasting monument to leadership and to those who have contributed so much to the campus. All of the names of those people involved with ODK since 1927 are engraved on the granite sides of the ODK Fountain, which was dedicated in April, 1997.