The collection consists of papers produced or collected by Heister Dean Guie, an author, journalist, and editor in Yakima, Washington. While there is some personal correspondence in the collection, the bulk of the correspondence relates to Guie's historical research, particularly the history of Fort Simcoe, Washington, and to efforts to restore Fort Simcoe as a historic site. Other topics discussed in the correspondence are Fort Simcoe's first commander, Robert S. Garnett; Louis Scholl, who designed Fort Simcoe; the Nez Percé War; and the Yakama people (written throughout the collection as "Yakima"). Substantial amounts of correspondence are with Ruth E. Peeler and Albert Culverwell of the Washington State Parks and Recreation Commission, Donald H. Clark, Leonard L. Lerwill, and Priscilla Knuth of the Oregon Historical Society. Other correspondents in the collection include U.S. Representative Hal Holmes, Z. F. Moody, Ben Olney, John Rea, Roscoe Sheller, Mary Ethel Semple Swanstrom, and descendants of Robert S. Garnett and Louis Scholl. There is also some correspondence between other people, and two letters from University of Michigan students whose connection to Guie is unknown. Other personal papers include biographical, career, and family information; poetry; and newsletters from the Cannon Hunters Association of Seattle (CHAOS). The collection also contains manuscripts of articles Guie wrote on historical topics and Guie's research materials, which primarily consist of transcribed primary sources, particularly from the U.S. Army and the U.S. government in the 19th century.

Other papers in the collection consist of: records of the Fort Simcoe at Mool Mool Restoration Society, records of the Yakama Agency (written as Yakima Agency or Yakima Indian Agency) and the school at Fort Simcoe, and records of and relating to the Yakama Tribal Council (written as Yakima). Yakama Agency and Fort Simcoe school records include a court docket book, financial records, correspondence, student records, school curricula, and a record book of the school mess. These materials date from the late 19th and early 20th centuries. Yakama Tribal Council records and related materials consist of minutes, resolutions, and statements, and a 1974 court brief relating to Native fishing rights.