The phenomena variously described as ‘nativistic’, ‘messianic’, or ‘reform movements’ have usually been very dramatic, have brought about important culture change, and have often occasioned some disquiet on the part of the authorities. One has only to think of the Ghost Dance, the Sudanese Mahdi, the Taiping Rebellion, and Mau Mau—among recent examples—to say nothing of the birth of Christianity and Islam. For these dynamic cultural innovations Anthony Wallace (1956) has suggested the term ‘revitalization movements’, of which there are thousands of documented cases throughout the world. Such movements are conscious, deliberate, and organized; they emerge out of acute social and economic dissatisfaction and as an attempt to create a more satisfactory culture.