In 1920-21, Patterson founded Pi Sigma Alpha, the political science honor fraternity. He served as the organization’s president from its founding until 1932. The idea of the organization came from senior members of his department, including Herman Gerlach James and Charles Grove Haines. Patterson carried out the vision, he wrote, because “You possibly have experienced the fact that the big boys in a department are very fertile in making suggestions for their underlings to execute.” Still, Patterson worked tirelessly to try to expand the organization, remembering that he “was young and full of vinegar.”14 Patterson “was constantly promoting the organization, trying to get new chapters established. That went slowly at first, but snowballed as time passed.” R. Taylor Cole, among the first initiates in the Alpha chapter at UT, said: “You will find the fine hand of Caleb Perry Patterson, mighty oaths of secrecy when we were initiated, and indirect evidence of a missionary zeal to conquer all” in the founding of PSA.

Patterson eagerly sought to make the organization national in scope. He set out on a road trip to Southern Methodist University, the University of Oklahoma, the University of Kansas, and Washington University in St. Louis to convince friends at those schools to begin chapters. These four schools, along with the University of Texas, were present at the initial meeting of the organization. He then mailed acquaintances across the country to ask if they wanted to establish chapters. Among the schools contacted were Stanford, the University of California at Berkeley and the University of Washington. These three universities had started their own organization, but decided that Patterson’s group had “an edge,” and they joined the fledgling Pi Sigma Alpha.16 By 1931, there were at least 17 chapters at some of the “larger universities,” and officers of the organization came from new member schools including Ohio State, Kentucky, Brown, and Bucknell.17 The Texas mafia were encouraged through Patterson’s efforts to “propagandize” for PSA. Two examples were the efforts of Sam B. McCalister at North Texas and Comer Clay at Texas Christian University. Patterson remained as president until 1932, when he handed the reins to Charles W. Pipkin of Louisiana State University. At that time, Patterson gained the title “honorary president for life.”