Saint Louis University is a private institution that was founded in 1818. It has a total undergraduate enrollment of 7,411, its setting is urban, and the campus size is 281 acres. It utilizes a semester-based academic calendar. St. Louis University is a Catholic, Jesuit school that is open to students of any faith. The Campus Ministry organizes specialized retreats and mission trips throughout the year, and the on-campus church holds a daily Mass. In addition to religious extracurriculars, students can also choose from more than 150 student organizations at SLU, including more than 20 fraternities and sororities. Freshmen and sophomores must live on campus, unless they commute from a parent's home, are married or have been in the military for at least two years, among other exemptions. In total, about 90 percent of freshmen live on campus – all in halls exclusively for first-year students. Students can get involved in campus leadership positions as early as the second semester of freshman year.