The George Teasdale papers (1770-1984) contain information regarding George Teasdale, an apostle for the Church of Jesus Christ of Latter-day Saints (LDS). Included in the collection are diaries, patriarchal blessings, correspondence, certificates, agreements, tax and financial documents, property deeds, notes, genealogy charts, and memorabilia. The collection is divided into three sections: personal, family, and religious materials.

The George W. Teasdale diaries and correspondence (1909-1936) consist mainly of correspondence between George W. Teasdale and his step-mother from 1910 to 1911. Teasdale was serving a mission for the Church of Jesus Christ of Latter-day Saints during these two years. Two diaries resulting from his service are also in the collection.

The Robert Temple papers (1938-1948) consist of materials regarding his marriage to Virginia Lee Clark, his career and his military service.

The Philip S. Thacher papers (1971-1989) contain biographical materials, photocopy of a scrapbook detailing his activities and a photocopy of a letter to the First Parish Church of Needham, Massachusetts "on its Bicentennial Anniversary." Thacher was a pastor of the First Unitarian Church of Salt Lake City, Utah.

The Thatcher family papers (1881-1904) consist of the missionary journals and letters of Roy Davis Thatcher and Diana Bean Thatcher.

The Third Saturday Night Dance Club records (1938-1999) contain membership lists and applications, by-laws, meeting minutes, correspondence, announcements of upcoming events, reports from the treasurer, and a history of the club prepared by Hope Shepherd. The Third Saturday Night Dance Club was organized about the year 1900.

The Ivor Delwyn Thomas papers consist of materials related to nuclear reactor and nuclear industry development along with personal correspondence and other materials. Thomas was an environmental chemist.

The Jack. E. Thomas papers (1927-2000) contain personal and professional correspondence, his dissertation, military and other documents, speeches and unpublished manuscripts.

The Jack Thomas papers (1928-1973) consist of various materials regarding Warren John "Jack" Thomas (1882-1973), a Utah railroad worker and member of the LDS Church's Tabernacle Choir. Included are biographical materials, correspondence, choir programs, news clippings, and Kiwanis Club papers.

The Lowell Jackson Thomas papers (1916-2010) consist of correspondence and articles by Terrell Dougan and others, biographical materials, and news clippings. Thomas was a radio and television broadcaster, author, and world traveler.

The Mark D. Thomas papers (1937-2006) contain his works as a contributor and chairman to the Sunstone Symposium and the Dialogue journal along with unaffiliated LDS research groups. It also contains papers from Thomas' time as a LDS Youth Seminary teacher, and his correspondence with the Church Education System.

The James Thompson diary (1887-1889) consist of a transcribed copy of the original diary of a missionary for the Church of Jesus Christ of Latter-day Saints. Accompanied by photocopies of family correspondence and genealogical records.

The Ralph D. and Ruth Thomson papers (1956-1972) center around the Golden Spike Railroad Centennial Celebration in 1969. The collection includes correspondence, invitations, name tags, pamphlets, and publications regarding the celebration, as well as the Thomson's personal correspondence.

The Chauncey L. Thornburg papers (1919-1970) concentrate on the work of Thornburg (1899-1986) as a mining geologist in Mexico. He received both a bachelor's and master's degree in geological engineering from the University of Utah. The collection includes correspondence, reports, essays, articles, maps, charts, and photographs, most of which were assembled into bound volumes by Thornburg.

The Gladys Thorne papers (1905-1920) consist of eight letters written by members of the MacNeil family. Seven of the letters are from Ann MacNeil of Wishaw, Lanarkshire, Scotland, to her neice, Annie MacNeil Henkel of Salt Lake City, Utah. The letters contain information about various family members. There is one letter to Annie Henkel from her cousin, David MacNeil, which concerns matters of family inheritance.

The Eva Lewis Tiemersma papers (1922-1924) consist of a diary (1922-1924), mission letters, and memorabilia from an LDS mission to the Eastern United States.

The David Brighton Timmins papers (1968-1989) consist primarily of materials relating to Dr. Timmins career in the United States Foreign Service, including correspondence, State Department memoranda, reports, and official documents. Also included are documents relating to his role in the establishment of the Department of Economics at Weber State University and papers regarding his tenure teaching economics at Instituto Tecnologico Y De Estudios Superiores De Monterrey.