Special Collections holds a rare book collection of over 40,000 volumes, with first editions of English and American literature from the 17th to the 19th centuries. Other strengths are in travel and exploration, natural history and ornithology, and works of historical significance in science and technology. Holdings in the history of technology are actively being expanded; they focus on large scale construction, such as works on bridge building and design, and iron and steel construction. Another focus is mining and metallurgy.
Special Collections also holds manuscripts and personal papers. Frequently consulted collections include the papers of Les Whitten, successful novelist and Watergate-era investigative reporter; the Congressional papers of Francis E. Walter; and the papers of the Lehigh presidents. In 2005, Lehigh acquired the Philip I. and Muriel M. Berman Archives. A collection of autograph letters has been digitized for research and curricular use in the I Remain project.
The Lehigh University Archives contains documents, photographs, and publications of the University, papers of faculty members, and Lehigh memorabilia. Special Collections is also the repository for Lehigh theses and dissertations and over 20,000 photographic images.