The Walter and Martha Leuba Papers contain materials related to the Leubas' collecting and writing pursuits, including manuscripts, research notes, clippings, the Leuba's collection of autograph and typescript signed letters, catalogs and indexes of their collections, and wood blocks. They reflect the Leubas' interests in books, art, literature, and music. In addition, the collection contains materials related to the Leubas' lives, family, friends, and other interests; these include correspondence, photographs, scrapbooks, diaries, and personal papers.
The bulk of the material in the collection dates from within the Leubas' lifetimes, 1902 to 1988. Material from before 1902 is primarily from their collection of signed letters (Series III, ALS and TLS) and family records (Series V, Personal Papers). Some of the material, particularly in Series V, Personal Papers, pertains to Pittsburgh, Pennsylvania, where the Leubas spent most of their adult lives; a small portion pertains to New York City, where Walter Leuba lived briefly.