The KITLV collections contain books, journals, magazines and newspapers, photos, picture postcards, prints and drawings, maps and atlases, Oriental and Western manuscripts and archives, and audiovisual materials. Approximately three-quarters of material in the collections pertains to Southeast Asia, in particular Indonesia, and one-tenth to the Caribbean, the rest of it being from or about Oceania and other parts of Asia and the Americas. Outside Indonesia itself, the KITLV Library is generally considered to hold the world's largest and best collection of written documents on and from Indonesia. Its Caribbean collection is also considered to be outstanding. Highlights of the collection include color glass negative from Woodbury and Page and archive collections of and about F.W. Junghuhn.

The Department of Collections aims to optimize access to its collections in a number of ways.

Most of the half a million books as well as manuscripts, archives, maps, audio and video tapes are searchable in our online catalogue. There is also an outstanding collection of archive inventories available on-line. In addition, the Southeast Asian Serials Index (SASI) provides access to articles published in dozens of international journals. Tens of thousands of photographs are digitally available on a dedicated website through which copies may also be acquired and to which new additions are made weekly. To facilitate subject searches our specialized thesaurus is available online.