Primary sources provide first-hand testimony or direct evidence concerning a topic under investigation. They are created by witnesses or recorders who experienced the events or conditions being documented. Often these sources are created at the time when the events or conditions are occurring, but primary sources can also include autobiographies, memoirs, and oral histories recorded later. Primary sources are characterized by their content, regardless of whether they are available in original format, in microfilm/microfiche, in digital format, or in published format. Primary sources can be found in nearly all of Yale's twenty-two libraries as well as at the Peabody Museum of Natural History, the Yale Center for British Art, and the Yale Art Gallery. See the “Tools for Discovery” page for tips on identifying materials relevant to your research.

For research using primary sources in the Yale University Library see: https://primarysources.yale.edu/

Throughout the special collections libraries and departments including the Manuscripts and Archives Department, The Divinity Library's Day Missions Collection and the Beinecke Library are found historical collections relating to Southeast Asia. Two distinctive collections that came to the library were the Maurice Durand Collection, which is particularly strong in literature, history, and civilization of Indo-China and the Yeh Hua Fen Collection, which consists mainly of books on Malaysia and Singapore.