Until the Fall of 1890, the number of girls in college was small, never more than 20 at one time, so that the plan of admitting all to Sigma Kappa presented no difficulties. In 1894, however, 15 women entered and all could not be admitted to Alpha chapter because of the membership limit of 25 set in 1879. It was decided to establish another chapter of the sorority on the campus, and the following year, the girls were divided between Alpha and Beta, meetings always being held jointly. In 1892, a third chapter, Gamma also on the Colby campus, was instituted to meet the needs of the class of 1896. A decision was reached to initiate no more girls into Beta and Gamma and to look beyond Colby for additional members. In 1904, a chapter was establish at Boston, and, in 1905, another at Syracuse. Thus the sorority grew steadily and soundly.

Colors of the sorority are Lavender and Maroon, the flower is the Violet. The Sigma Kappa jewel is the Pearl. The open motto is "One Heart, One Way". The Sigma Kappa badge is an equilateral gold triangle supporting a raised triangle of maroon enamel bearing the greek letters  in gold. The pledge pin is gold, the letter K with a serpent entwined through it in a form of an S.

The History was first published in 1924, and at the 100th anniversary convention, a Centennial History was published. An anthology of verse by Sigma Kappa was published in 1936, commemorating the 60th anniversary. Other publications include an Advisory Board Handbook, Constitution and By-laws, National Policies, Songs of Sigma Kappa, The Brave Maroon II, Pledge Manual, and Speaking of Sigma Kappa.

The purpose of Sigma Kappa Sorority is to unite its members in a bond of sincere friendship for the development of character and the promotion of social, literary, and intellectual culture to support and further the program and objectives of the colleges where its chapters are functioning; to strive for high standards of achievement scholastically, socially, and spiritually; and to make a constructive contribution to the communities in which its collegiate and alumnae clubs are located by encouraging the exercise of the rights and obligations of good citizens and the support of worthwhile civic, social, and philanthropic projects.

Sigma Kappa Sorority is a social organization of collegiate and alumnae women committed to promoting the ideals of life-long friendship, intellectual and spiritual fulfillment, and service for the greater good.

The vision of Sigma Kappa is to be a premiere Sorority, forever achieving excellence in our chapters and among our members and influencing the lives of others.