George Rapp (1757-1847) - lauded by the Pittsburgh press, after his death, as the "greatest communist of his age" - founded Rapp's Harmony Society, the most successful American communist group. The Harmony Society attempted to carry out its interpretation of the prophecy concerning the Sunwoman according to the Book of Revelation. Needing more space, the Harmony Society left its first American settlement (Harmony, Pennsylvania) and settled in Indiana Territory, where the society began its second decade in America. Establishment of the efficient commonwealth influenced the political development of Indiana; politicians seeking office considered it wise to take the Harmony Society into consideration. The State borrowed money from the society on occasion. Many persons from all over the world wrote to inquire about the remarkable success of the communal society. Evidently the answer lay in its unselfish industry and religious zeal. Without the religious impulse, Robert Owen's New Harmony failed in two years, while the Harmony Society moved on to its third new start and further great accomplishments. Based on unpublished letters and documents; 6 illus., 3 notes.