Founded on August 16th, 1850 at the University of Pennsylvania, Phi Kappa Sigma was the brainchild of, then student, Dr. Samuel Brown Wylie Mitchell. At the time, secret fraternities were springing up across the country as a means to combat commonplace censorship of students by university administrators. Inspired by the establishment of the Delta Phi and Zeta Psi fraternities on the University of Pennsylvania's campus, Dr. Mitchell resolved to gather men who shared his values and create a new fraternity which would exemplify his beliefs in enlightened manhood. The Fraternity rapidly grew from the University of Pennsylvania campus until the advent of the Civil War. In 1860, the Fraternity's membership unanimously rejected a proposal to segregate. Phi Kappa Sigma has been proudly accepting of all men since our founding. 

The Civil War had a large impact on the American Greek System. Many chapters were forced to go inactive as their members fought and died in the war, leading to a sharp decline in the number of fraternity men. Phi Kappa Sigma was buoyed through the Civil War by the efforts of two young alumni, Robert H. Mcgrath and Edmund Cash Perchin, who managed the fraternity's affairs, communicated with brothers on both sides of the conflict, and helped finance the care of brothers in union prison camps. Though the country was divided, Phi Kappa Sigma was not. Early alumni chapters smuggled southern brothers to hotels in the north to socialize with their northern counterparts, most notably at the St. Nicholas Hotel in Cumberland. Southern brothers, nicknamed 'Silver Skulls', wore pins which indicated their membership in the fraternity so that they might not be harmed by northern brothers in battle.

After the end of the Civil, Phi Kappa Sigma entered a period of conservative expansion which exists to this day. During that time, the fraternity served as a founding member of the National Interfraternity Council (NIC), which is the primary governing body of Greek Life in the United States and Canada. 

During the early 1980's, several students at Carthage College in Kenosha, Wisconsin were looking for a different fraternal experience than the one that was available on campus. They moved to establish a new national fraternity at Carthage, initially discussing chartering with the Sigma Chi National Fraternity. To comply with IFC rules, the men first established a local chapter, Sigma Chi Omega, with the intent to convert the local to a national within a year. 

Due to disagreements with the headquarters of Sigma Chi, aided by courting from several other national fraternities, the young men began to search for a new national charter. The men visited several chapters and decided to charter to Phi Kappa Sigma after an impactful visit to the Alpha Beta Chapter at the University of Toronto. 

The Gamma Gamma Chapter of Phi Kappa Sigma was colonized in 1983, being chartered with 23 founding members in Spring of 1984. The Chapter has grown to more than 30 members and was the runner up for Most Distinguished Chapter for the 2016-2017 school year.