Creator's Description: In 1926 the botanist/scholar Joseph F. Rock (1884-1962) acquired a complete set of the Co ne Bka' 'gyur and Bstan 'gyur for the Library of Congress (LC) in Washington, D.C. This set is considered one of the rarest treasures of the Tibetan rare book collection at the LC. It is also considered especially rare among scholars worldwide since the original eighteenth century wood blocks from which it was printed were destroyed by fire in 1929. In this paper the history of its acquisition by the Library and attempts to preserve and disseminate it are described.