In 1917, the university had four faculties: Arts and Sciences, Public Administration, Engineering, and Medicine. The Faculty of Law was established in 1933 as part of the Faculty of Law and Political Science. From the 1930s to the 1950s it expanded to various fields including Pharmacy (1934), Veterinary Science (1935), Architecture (1939), Dentistry (1940), and Commerce and Accountancy (1943). In 1943, the regency government under General Phibun separated the Faculty of Medicine, Dentistry, Pharmacy, and Veterinary Science to become the University of Medical Sciences, now Mahidol University. In 1948, the Faculty of Political Science was re-established. The Faculty of Education was established in 1957 from the School of Teacher Training at Baan Somdet Chao Phraya (). In 1967, the Faculty of Veterinary Science was returned from Kasetsart University and the Faculty of Medicine at Chulalongkorn Hospital was moved from University of Medical Sciences to Chulalongkorn University. In 1972, the Faculty of Dentistry and Faculty of Pharmacy were reinstated.