Sigma Kappa Sorority was founded at Colby College in Maine in 1874.
Colby College was the first college to allow women admittance on equal terms with male students. Only one female, Mary Caffrey Low, entered the first year. Four more women entered two years later. These five women constitute the founding class of Sigma Kappa Sorority. Even though they were allowed as students at Colby, their presence evoked opposition from both male students and professors. This only served to bring the five women together in a bond of friendship. They presented a constitution, bylaws, and a petition requesting permission to form a Greek-letter society to the College administration. On November 9, 1874, the young women received a letter from the faculty approving their petition for Sigma Kappa Sorority. This date has since been considered our Founder's Day.

In February 1875, two more women were initiated into Sigma Kappa, giving the new society seven members in their first year. Small and informal meetings were held regularly. Business sessions were recorded in detail and the first banquet was held on November 30, 1878. In 1881, the women of Sigma Kappa found themselves the recipients of serenading from one of the men's fraternities at Colby College.
Our first constitution limited the membership to 25. The original group, known as the Alpha Chapter, preceded the Beta and Gamma Chapters, also at Colby College. The groups met together, but eventually the Beta and Gamma Chapters vanished from campus. It was around this time that the Sorority decided to expand beyondColby College. In 1904, Delta Chapter was installed at Boston University. Elydia Foss, Alpha, Colby College, took the necessary steps to make Sigma Kappa a national sorority which was incorporated in the state of Maine on April 29, 1904. Their national status made Sigma Kappa eligible to join what was then called the Interfraternity Conference, now known as the National Panhellenic Conference.
Famous Sigma Kappas
- Margaret Andrews, Chi: inventor and experimental engineer, improved the engineering of dishwashers, inducted into the Ohio Women's Hall of Fame.
- Fay Burnett, Sigma: first nutritionist for Weight Watchers International, writing its first maintenance plan.
- Linda Cross Dowdy, Epsilon Epsilon: creator and owner of Barney, the popular purple dinosaur featured on PBS, authored the best-selling children's book, Barney Goes to the Zoo.
- Anna Harper, Lambda: 1931 Wimbledon tennis champion, National President of Sigma Kappa from 1939 to 1942.
- Susan Johne, Alpha Chi: Kentucky State senator, 1994.
- Judith Guest la Vercombe, Alpha Mu: author of Ordinary People, which has since become a motion picture.
- Betty Jo Peacock Hay, Sigma: president of the National Mental Health Association in 1986, received such honors as the Hogg Foundation for Mental Health Award and Public Citizen of the Year.
- Lauren Roman, Theta Zeta: plays Laura Kirk on the daytime drama, All My Children.
- Rhea Seddon, Lambda: mission specialist for NASA, first flight into space was aboard the Space Shuttle Discovery in 1985, taking her Sigma Kappa badge on her flight.
- Margaret Chase Smith, Alpha: first U.S. woman senator, first woman to sit in both houses of Congress, recipient of the U.S. Air Force's most prestigious award, the American Spirit Award and Presidential Medal of Freedom Award.
- Ashley Welkos, Gamma Theta: plays Jessica Forrester on the CBS daytime drama, The Bold and the Beautiful. Her stage name is Maitland Ward.
- Sarah Weddington, Zeta Nu: first woman elected from Austin to be a member of the Texas House of Representatives in 1972, assistant to President Jimmy Carter, argued before the U.S. Supreme Court for Roe v. Wade case, which she won in 1973.