The Paul Thatcher family papers (1809-1972) contain diaries, letters, biographies, and reminiscences from two prominent families of Utah, the Thatcher's of Logan and the Smoot's of Provo.

The Daniel Hadlond Thomas papers (1939-1992) consits of a re-edited version of a biography of Preston Thomas originally completed in 1942. It includes transcriptions of missionary diaries. Also included in the collection is correspondence and a poem written by Thomas.

The George Thomas diary (1849-1868) contains a personal and family record. The journals speak of his conversion to the Church of Jesus Christ of Latter-day Saints (LDS Church).

The Wanda Clayton Thomas papers (1839-1992) contain materials concerning Wanda Clayton Thomas (1912-1996) and her heritage, concentrating on the descendants of Newell H. Clayton.

The Henry B. Thompson diaries (1899-1900) consist of photocopies of the originals detailing Thompson's mission for the Church of Jesus Christ of Latter-day Saints (LDS Church) in Scotland. In these diaries, Thompson describes the challenges that he faced as a missionary. Thompson was appointed president of the Scottish Conference in May 1900 and returned to Utah in June of 1901.

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 Louisa Wagoner Thorne diaries [photocopies] were written from 1927-1929 and recount events she experienced while living on Willow Creek, near Vernal, Utah, including acquaintances with several members of the Ute Indian tribe.

The Vinzenz Thum diary (1919-1922) is handwritten and was kept while on a mission for the LDS Church in Canada and eastern United States.

The Albert King Thurber papers (1822-1877) contain transcripts of his autobiography and a partial diary. Thurber was convert to the LDS Church. He served several missions, including one to England in 1865. He was also a member of the Utah legislature, and later served as a delegate to the legislature.

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 Helon Henry Tracy papers (1875-1889) contain diaries, journals, bookkeeping ledgers, prison inmate rosters, articles, research materials, and newspaper court reports. Tracy was a member of the Church of Jesus Christ of Latter-day Saints imprisoned for polygamy in Utah in 1886.

The Roy and Wuta Terazawa Tsuya papers (1906-2013) contains correspondence among family and friends, records from their work with the LDS church, as well as memorabilia from Roy's membership with the 442nd Regimental Combat Team and Boy Scouts. The collection also contains one box pertaining to Chiye Terazawa, Wuta's sister.

The Shirley E. Blackmer and R. Lloyd Tyler family papers (1902-2013) consist of correspondence, scrapbooks, genealogical records, journals, and other documents. Shirley and R. Lloyd Tyler were devout members of the LDS Church and were also business owners of a store located in Walla Walla, Washington. Items of interest include the correspondence and scrapbook regarding R. Lloyd's experiences during World War II.

The Helen Bowring Ure papers (1930-1989) contain correspondence, awards, clippings, scrapbooks, and papers relating to national bodies of the P.T.A., Board of Education, Y.W.C.A., and the Women's Legislative Council of Utah, as well as the Ure and Bowring families. Includes correspondence and memorabilia of her husband, James W. Ure III.

The Richard Dean "Dick" Wallin papers (1964, 1973) consist of photocopies of a diary entry regarding his experience traversing Wind Rivers, Green River Lakes, and Trail Creek. Also included in the collection are two news clippings. One discusses the Alpen Bock Climbing Club, and the other discusses a mountain rescue crew of the Salt Lake Area.

The Andrew H. Wardle diary (1877-1897) chronicles some of his family genealogy, his own story and that of his father and grandfather. Wardle's grandfather, George Wardle, came West with Brigham Young.

The Ardean Watts papers (1928-2015) contain his professional, personal, and general material. Watts was a prominent figure in the Utah arts community.

Incomplete diary (1963) of an LDS missionary, Kurt Randolph Wegner, to the South German Mission.