The library was completed in 1964 and named in honor of Rex A. Dunn, a Simpson alumnus. A major remodel was completed in 2023; the building reopened in 2024. The first floor houses The Center for Academic Resources (CARs), TRiO Student Support Services, the Teacher Education Department, and the Curriculum Lab. The second floor includes the Research Assistance Center, Library Services desk, and physical collections (books, journals, scores, and DVDs); e-books, e-journals, and many e-resources are available through the library’s website. Special Collections houses an Antebellum South collection, along with Asian art books and the Lehmann Collection of Ancient Pottery. Dunn also features group study rooms, individual carrels, and other collaborative spaces. The third floor includes quiet collaborative spaces and the Walt Research Library & Simpson College Archives. The first library building, the Carnegie Library located by Mary Berry Hall, was completed in 1907 with Carnegie funds and was taken down in June 2014.