Materials are acquired through both donation and purchase. Selection of materials to be added to Special Collections is made on the basis of their age, uniqueness or rarity, provenance, format, and subject.
The book collection consists primarily of North American editions published prior to 1850, British imprints prior to 1800, and European imprints prior to 1750.
In addition, numbered limited editions, examples of fine printing or binding, editions with fine or unusual illustrations, local imprints and books relating to local history are collected.
Unique archival materials and manuscripts are also kept in Special Collections. Finally, Special Collections houses certain non-paper materials: selected sound recordings, films, slides, and realia.