The Ku Klux Klan Collection contains materials related to the Ku Klux Klan in the Walla Walla Valley. This collection, which dates from 1912 to 1999, consists of articles, application forms, and research related to the Ku Klux Klan and its presence in the Pacific Northwest.

The Penrose Family Papers contains materials related to Dr. Stephen B. L. Penrose, who served as Whitman College President from 1894 to 1934, his wife Mary Shipman Penrose, and their children: Mary "Maysie" Penrose, Virginia Penrose, Frances Penrose Owen, Clement Biddle Penrose, Nathanial S. Penrose, and Stephen B. L. Penrose, Jr. The collection includes correspondence, diaries, travel journals, photographs, and biographical and genealogical information.

Stephen B. L. Penrose, Jr. Papers chiefly contains the correspondence of Stephen B.L. Penrose, Jr., depicting his presidency of the American University in Beirut, Lebanon, from 1948-1954, his involvement with the Office of Strategic Services (OSS), his work with the United Nations Educational, Scientific, and Cultural Organization (UNESCO), and his views on and advocacy for Palestinian statehood and Palestinian refugees.