Thammasat’s first library was established at the founding of the university in 1934. Initially, the library was under control of the administration and was known as the Textbook and Library Division.
In 1958, control was transferred to the Educational Services Division, and again in 1961 to the Office of the Rector. In 1976 the library attained the status of an independent office (the first in Thailand), with all branches becoming centralized under the administration of the Thammasat University Library System. At this time the system included the central libraries as well as branch libraries for the Faculty of Law, the Faculty of Commerce and Accountancy, the Faculty of Political Science, the Faculty of Economics, the Faculty of Social Administration and the Faculty of Sociology and Anthropology, the Faculty of Journalism and Mass Communication and the Institute of Thai Studies.
When the university expanded to its Rangsit Campus in Pathum Thani, the library system expanded as well. 1986 saw the founding of the Rangsit Campus Library and the Library of the East Asia Institute, followed by the Faculty of Medicine Library in 1991 and the Puey Ungphakorn Library in 2002. The Faculty of Social Administration, Sociology and Anthropology Library was closed in 2006 and transferred to the central branch (The Pridi Banomyong Library), and in 2007 the Library of the East Asia Institute was closed as well and integrated into the Puey Ungphakorn Library.
The expansion continued as the university added campuses in both Lampang and Pattaya. Founded in 1997, the Lampang Campus Library was established in 1997 but was not integrated into Thammasat’s larger library system until 2004. The Pattaya Campus Library was established in 2006 and integrated soon after.
In 2008, the Faculty of Commerce and Accountancy library was renamed in honor of Professor Sangvian Indaravijaya.
In 2009, the university council approved a plan to implement the following improvements to the library system :
1. Streamline the chain of command, reducing the previous 3 branches (Administration and Development / Technical / Service) to 2 (Administration and Development / Service and Information Literacy)
2. Combine the Collections Development Division and Collections Analysis Division to form the Collections Management Division for enhanced integration of work techniques. The Collections Management Division falls under the Administration and Development branch in the chain of command, alongside the divisions of Library Promotion and Development, Library Technology, Collection Preservation and Office of the Secretary.
3. Establish the new Serials Division under the Administration and Development branch, to improve the quality of service and capability of staff to complement increase in services.
4. Establish the budget, finance and accountancy position under the Office of the Secretary, to increase the ease of library budgeting due to increase in endowment.
5. Discontinue the Educational Media Service Center, to be replaced by the Educational Media Service
at the PridiBanomyong library to lessen workload responsibilities, following the cut of 3 audiovisual positions in the university.
In 2010 the university council passed the following resolutions :
1. The Lampang Campus Library will be renamed the BoonchooTreethong Library
2. The Thammasat Medical Library will be renamed the Nongyao Chaiseri Library
3. A section of the Rangsit Campus Library will be converted to a book bank for the storage of low-circulating items from any branch.
In 2011, Thammasat University's Rangsit Campus received massive damage from the October-December floods. The flood levels reached approximately 1.70 meters, causing damage to the entire 1st floor of the Puey Ungphakorn Library. Besides total damage to all the books in that area, there was widespread damage to the tables, chairs, walls and tiled floors. Undamaged materials were relocated to the 2nd floor. As a result, the Puey Ungphakorn library was closed from October to December 2011, with the 2nd and 3rd floors closed a further month, through to start of term in January 2012. Rehabilitation of the Puey Ungphakorn library began in December 2011, finishing in January 2012 through a bond of 50,000,000 baht from the university, a donation of 3,799,500 baht from the Hitachi company of Japan, as well as a budget of 28,550,400 from the government, for a combined total of 82,349,900 baht towards the repair efforts.
Apart from the Puey Ungphakorn Library, the one-story Rangsit Center Library, housing the book bank, also received a great amount of damage. Although some books were prepared and bound for movement to the upper floor, the water levels reached 70 centimeters and faced similar damage as the PueyUngphakorn library; tables, chairs, walls and tiled floors and air conditioning units, as well as approximately 50,000 books. About 30,000 of these books were found to be beyond repair. The restorations underway at the Rangsit Library include eliminating fungus on the damaged books, replacing the rubber flooring tiles with granite. The rehabilitation was finished in December 2012, with an additional bond of 6,800,000 from the university.