* Phi Sigma Sigma was founded at Hunter College in New York City, New York on November 26, 1913. It was the first non-sectarian sorority, the only one open to diverse membership from its inception and the only one with a ritual not based in scripture.
* Lilian Gordon, Ethel Gordon, Josephine Ellison, Sirley Cohen, Fay Chertkoff, Claire Wunder, Estelle Melnick, Rose Sher, Jeanette Lipka and Gwen "Rae" Zaliels were the names of the women bold enough to create their own sorority.
* First in the minds of these women were the two twin ideals which still endure to this day. Each Phi Sigma Sigma sister extends herself to help promote the brotherhood of man and to the alleviation of the world's pain.
* The year 1918 also saw the first National Convention of Phi Sigma Sigma. Fay Chertkoff was elected as the first Grand Archon of Phi Sigma Sigma. The first Supreme Council served from 1918 until 1920. Fay Chertkoff was elected as the Grand Archon, with Ethel Gordon Kraus as the Grand Vice Achon, Shirley Cohen Lauger Goldstein as the National Tribune and Estelle Melnick Cole as the National Bursar.
* Phi Sigma Sigma becme truly a national sorority when Zea Chpter was installed at the University of California at Los Angeles in 1921. Phi Sigma Sigma was the first national sorority at UCLA.
* In 1930, Phi Sigma Sigma became an international sorority with the founding of Upsilon Chapter at the University of Manitoba in Manitoba, Canada.
* Phi Sigma Sigma's first double letter guard, which signifies the beginning of the Greek alphabet again, was given to the Beta Alpha Chapter at the University of Maryland in 1936.
* In 1943, the name of the national headquarters was changed back to Central Office and the first Executive Secretary was hired. Esther Malter was Phi Sigma Sigma's first paid staff member. At that time, the headquarters of the Fraternity moved from York, Pennsylvania to New York City, New York.
* At the 25th Convention in June 1950 in Bedford Springs, Pensylvania, the Convention body adopted a new design for the Phi Sigma Sigma badge, which had remained unchanged since Phi Sigma Sigma's founding. The newly adopted badge was similar to the original design with minor changes.
* In 1951, Phi Sigma Sigma became a member of the National Panhellenic Conference (NPC). Clarisse Harrison Markowitz served as the NPC Delegate.
* The Phi Sigma Sigma Cardiology Laboratory ws established at Yeshiva University Medical School in New York City in 1957. Phi Sigma Sigma presented a $20,000 grant to establish the laboratory.
* Phi Sigma Sigma celebrated its Golden Anniversary at the Waldorf-Astoria in New York City in 1963.
* In 1966 Leadership Training School was introduced by Jeanine Jacobs Goldberg. This is held in years when there is not a National Convention. The purpose of LTS, held on a national basis, was to replace divisional meetings to more successfully meet hte training and informational needs of the collegiate chapters, alumnae chapters, and national personnel.
* In an effort to give greater emphasis to the philanthropic activities of Phi Sigma Sigma, a national foundation, The Phi Sigma Sigma Foundation, was created by the 1969 National Convention. at the 1971 Convention, the National Kidney Foundation was adopted as the Fraternity's official philanthropic cause.
* Phi Sigma Sigma assumed a seat on the Executive Council of the National Panhellenic Conference in 1985, 34 years after being admitted. In 1991, Phi Sigma Sigma's Louise Kriegsman Kier assumed the Chairmanship of the NPC.
