The John Taylor family papers (1844-1994) are a collection of material reflecting the life and work of John Taylor, third president of the LDS Church, and his descendants, John W. Taylor, Raymond Woolley Taylor, and Samuel Taylor. Included are correspondence, letters, biographies, research, writings, diaries, and other papers.

The John W. Taylor family photograph collection contains portraits of John W. Taylor, various wives, and members of the Taylor family. The collection also contains portraits of members of the Woolley family, portraits of various leaders of the LDS Church, and miscellaneous photographs, many documenting research by Raymond and Samuel Taylor for the book entitled: Uranium fever.

The Joseph Edward Taylor diary [typescript] (1849-1877) consists of brief entires that cover certain events in Taylor's, and his family's, life. The diary covers events in Taylor's life such as converting to the Church of Jesus Christ of Later-day Saints (LDS), in England, his trip aboard a steamer to New Orleans, his travels from Council Bluffs across the plains to Salt Lake City, and the "Utah War" and the impact of the army at Fort Bridger and Camp Floyd.

The Raymond Woolley Taylor essay is entitled, "The Legend of the Friends to the Martyrs: The Initiators of the Oath of Vengeance." The essay presents a historical basis of the clandestine organization "friends of the martyrs" that assembled to avenge the murders of Joseph and Hyrum Smith. Raymond Woolley Taylor was grandson of LDS Church President John Taylor.

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 Teasdale photograph collection contains photographs of George Teasdale's life, family and LDS mission. The collection also contains several photographs of LDS Church leaders.

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

The Jean C. Thatcher family papers (1892-1953) contain a journal written by Jean C. Thatcher. The collection also contains a little booklet of the Thatcher cemetery plot, and a wedding announcement for Jean's brother.

The Moses Thatcher diaries consist of 4 volumes of photocopied originals and 1 original diary written by Thatcher of his LDS Church mission to Mexico and the British Isles.

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 Daniel Hadlond Thomas photograph collection consists of photograph of Daniel H. Thomas and his family.

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 John "Jack" Thomas photograph collection contains personal photographs of former agent for the Union Pacific Railroad and tenor for the Mormon Tabernacle Choir in Salt Lake City.

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 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.