Starting with The Teachings of Don Juan in 1968, Castaneda wrote a series of books that describe his training in shamanism, particularly with a group whose lineage descended from the Toltecs. The books, narrated in the first person, relate his experiences under the tutelage of a man that Castaneda claimed was a Yaqui "Man of Knowledge" named donJuan Matus. His 12 books have sold more than 28 million copies in 17 languages. Critics have suggested that they are works of fiction; supporters claim the books are either true or at least valuable works of philosophy.
Castaneda withdrew from public view in 1973, living in a large house in Westwood, California, with three colleagues whom he called "Fellow Travellers of Awareness." He founded Cleargreen, an organization that promotes "Tensegrity", which Castaneda described as the modern version of the "magical passes" of the shamans of ancient Mexico.
Castaneda moved to the United States in the early 1950s and became a naturalized citizen on June 21, 1957. He was educated at UCLA (B.A. 1962; Ph.D. 1973). Castaneda married Margaret Runyan in Mexico in 1960, according to Runyan's memoirs. Castaneda is listed on the birth certificate of Runyan's son C.J. Castaneda as his father even though his biological father was a different man. It is unclear whether Carlos and Margaret were divorced in 1960, 1973, or not at all, and his death certificate even stated he had never been married.