On February 14, 1916, Phi Sigma Pi was founded at State Teachers College at Warrensburg, Missouri and originally named Phi Sigma Pi Honorary Professional Fraternity. The three founders, Dr. Eldo L. Hendricks, Dr. Claude A. Phillips, and Dr. Clarence H. McClure, decided that Phi Sigma Pi would stress not only scholarship, leadership, and fellowship, but to do so in a concept of an equal tripod dedicated to these three ideals.
In 1966, it was suggested that an honor fraternity open to all academic majors which stressed scholarship, leadership, and fellowship would preserve the tripod, whil creating new opportunities for expansion.
The National Constitution was amended to admit eligible women in 1977. Phi Sigma Pi became a co-educational fraternity. Women were admitted into Phi Sigma Pi beginning in the fall semester of 1977. The word, "Brother," as all male members had historically called each other, would now come to refer to both men and women. The decision to admit females had an enormous impact on Phi Sigma Pi in the late 1970's and it continues today.