This collection contains the papers of Moses Thatcher, Sr. and his family spanning the period of 1866 to 1923. This collection contains Moses Thatcher, Sr.'s diaries (in photocopy form, original diaries are in the possession of Brigham Young University), correspondence, papers concerning his family, and other papers. His diaries document his missionary service in Great Britain from 1866 to 1868, his Presidency of the Cache Stake from 1878 to 1881, his ordination as an L.D.S. Apostle in 1879, and his work concerning the opening of the Mexican Mission for the L.D.S. Church and the beginnings of Mormon colonization in northern Mexico. Other items included are Thatcher's two correspondence letter-books (1888-1890 and 1902-1903), a Memoranda Book (1879-1880) which contains information about his work in Mexico, and a family scrapbook. This collection also contains the missionary diaries of Moses Thatcher, Jr. (in photocopy form) spanning the period of 1891-1892, Moses Thatcher, Jr.'s papers concerning his studies at the Logan Brigham Young College, various biographical sketches, and other papers concerning family affairs. The Moses Thatcher Sr. family photo album, was removed and has been reassigned as part of the Thatcher Family Photograph Collection (P0036).

Laurel Thatcher Ulrich later donated a letter from Moses Thatcher in September 2011.