The College of Arts and Sciences (CAS) (formerly the College of Liberal Arts (CLA)) is Boston University's largest undergraduate school, offering Bachelor of Arts degrees in 23 different departments and 20 interdisciplinary programs. The programs are divided into four broad categories encompassing over 2,500 courses, including natural science, social science, humanities, and math & computer science. About half of the students at Boston University are enrolled through the College of Arts and Sciences, while almost all students take a few courses through the school during their academic career.