Copublished with the Tanner Trust Fund, J. Willard Marriott Library. Leonard Arrington is considered by many the foremost twentieth-century historian of Mormonism. He played a key role in establishing the Western History Association and the Mormon History Association, and more than a half-century after its publication, his revised doctoral dissertation, Great Basin Kingdom: An Economic History of the Latter-day Saints 1830-1900, remains a standard. But Arrington's career was not without controversy. Gregory Prince takes an in-depth look at this respected historian and, in telling Arrington's story, gives readers insight into the workings of the LDS Church in the late twentieth century. In 1972, during a major reorganization of the LDS Church, Arrington was asked to serve as the official church historian, thereby becoming the first--and thus far the only--professional historian to hold that title. He immediately set out to professionalize the entire Church History Division and open its extensive archives to scholarly researching. While the output of and from that division moved Mormon studies to a new level, the shift of historiography from faith promotion ecclesiastical, to scholarly and professional research and analysis was unacceptable to a handful of powerful senior apostles. In 1980 the History Division was disassembled and moved to Brigham Young University. That led to a shift in the professionalization of the Church History Division and Archives and in Arrington's career but not to a loss of his broad influence. This biography is the first to draw upon the remarkable Arrington diaries (over 20,000 pages); it is supplemented by the author's interviews of more than 100 people who knew or worked with Arrington. The book is of additional significance given continuing battles between the LDS Church and scholars, which frequently gains national attention because of excommunications of prominent intellectuals.  Winner of the Evans Biography Award and the John Whitmer Historical Association's Brim Biography Book Award.