The Wolves of Heaven is a most unusual and challenging work. Published more than half a century after the classic Cheyenne studies of George Bird Grinnell and G. A. Dorsey, it is a singular reinterpretation of the Cheyennes' world view, shamanism, and major cultural features. It is the product of the author's blending of the principles of action anthropology with those of cognitive anthropology, his long field association with the Southern Cheyennes, and his close personal relationship with Edward Red Hat, the Cheyenne Keeper of the Sacred Arrows, who instructed him in Cheyenne religion for more than ten years. Along with important oral testimony, the book makes use of the great volume of works in the ethnography, ethnohistory, prehistory, and linguistics of the northern plains, the Subarctic, and northern Siberia. The core of the book is a reconstruction of the Massaum, the most elusive of Cheyenne tribal ceremonies, extinct since 1927. In a detailed interpretation of the ritual, provided here for the first time, the author defines the Massaum as an earth-giving ceremony. The gift of this ceremony between 500 and 300 B. C. in what is now South Dakota brought about the formation of the Cheyennes as a tribal unit with the right to occupy a large region of the grasslands.