In 1871, Colby College in Waterville, Maine admitted the first female student, Mary Caffrey Low. As a result, Colby College became the first college in New England to admit women on an equal basis with male students.

In 1873, four more young women from Maine, Elizabeth Gorham Hoag, Ida Fuller, Frances Mann, and Louise Helen Coburn, were admitted to Colby, and the five young women found themselves frequently together.

During the school year of 1873-74, the five young women decided to form a literary and social society. They were told by the college administration that they needed to present a constitution and bylaws with a petition requesting permission to form Sigma Kappa Sorority. They began work during that year with an eager glow of enthusiasm. Their purpose at the outset was that the sorority should become what it is now, a national organization of college women. On November 9, 1874, the five young women received a letter from the faculty approving their petition. Thus, this date has since been considered our Founders' Day. In 1891, lavender and maroon were first mentioned as the sorority colors.

In 1904, Delta chapter was installed at Boston University. Elydia Foss of Alpha chapter had transferred to Boston and met a group of women who refused to join any of the other groups on campus. Elydia Foss took the necessary steps to make Sigma Kappa a national sorority and it was incorporated in the state of Maine on April 19, 1904. The new status as a national sorority made Sigma Kappa eligible to join what was then called the Interfraternity Conference, now known as the National Panhellenic Conference. The Delta chapter of Boston University is now the oldest existing chapter.

Since its founding, Sigma Kappa Sorority has initiated more than 156,000 members worldwide. Today we have 110 collegiate chapters in 36 states and 120 alumnae chapters in 40 states. As of 1936, our national headquarters has been located in Indianapolis, Indiana.