World War II caused enrollment to decline and the student body consisted mainly of high school students and seminarians. Following the war, new students enrolled, and the school built a temporary facility in 1947 to accommodate them. Students from Illinois began to replace out-of-state students, the percentage of day, or commuting, students rose, and the school employed more lay teachers. After the war, the previously ethnic Czech college acquired a more diverse student body, due to rising enrollment caused by the G.I. Bill. By 1947 the high school enrolled 30 students. Better times and higher birth rates led to growing enrollment at St. Procopius in the 1950s and 1960s.