In 1915, because of class schedule conflicts, it was impossible to continue as a luncheon club and the organization became a society open to all women in attendance at the college. A new meaning was given to the Greek letters and Sigma was added to its name. During the year, an official badge, motto, flower, and colors were selected. The first steps toward becoming a national organization were taken in 1917, and the following year, the society became a secret and selective sorority, with the Boston group forming its Alpha chapter. Soon, other chapters were established. Also in 1919, the official coat-of-arms, designed by Cora E. Craven, was adopted.
The Council of Alpha Chapter conducted the national affairs of the sorority until May 1922, when a Graduate Grand Council was organized. By 1923, interest in the establishment of alumni chapters had grown, and the first two were chartered.
The first national convention was held in 1926 in Boston, Massachusetts. The first issue of the TRIANGLE was published and presented in mimeographed form to the convention-at-large. In 1928, it was decided that it should be traditional to observe Hygeia Day by the presentation of a professional program.
On April 28, 1956 Lambda Kappa Sigma became international with the addition to our ranks of Alpha Lambda chapter in Vancouver, British Columbia, Canada.
In 1964, support of Project Hope became our international philanthrophy. In 1968, the term sorority was officially replaced by the term fraternity in referring to Lambda Kappa Sigma.
Our first sisters from Kobe, Japan were initiated at the 1988 convention. As a result of civil rights legislation, the convention body voted to delete all gender references from our membership requirements. Thus, the Fraternity opened its membership to both females and males. Our Omicron chapter of Lambda Kappa Sigma was established on April 4, 1930. Our alumni chapter was established in January of 1942.