The Cullman Library holds the Smithsonian's collection of rare books in anthropology and the natural sciences. Its world-class collection contains approximately 10,000 volumes published before 1840 in the fields of physical and cultural anthropology, ethnology, Native American linguistics, and archeology; botany; ornithology, mammalogy, herpetology, ichthyology, entomology, malacology, and other zoological fields; paleontology; and geology and mineralogy. The publications of seventeenth- through nineteenth-century voyages of exploration are a special strength, as is the history of museums and scientific collecting. All holdings are cataloged and searchable in the SIL online catalog SIRIS.

The Cullman Library makes the books available to researchers by direct access in the reading room and through reference assistance (including limited photocopying when possible). In addition, the Library shares the collection by means of digital editions, exhibitions, exhibition loans, and public programs.