Castaneda moved to the United States in the early 1950s and became a naturalized citizen on June 21, 1957.

Castaneda married Margaret Runyan in Mexico in 1960, according to Runyan’s memoirs. Castaneda is listed as the father on the birth certificate of Runyan’s son C.J. Castaneda even though the 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.

He received his B.A. from UCLA in 1962, and Ph.D. in anthropology in 1973.

After Castaneda stepped away from public view in 1973, he bought a large multi-dwelling property in Los Angeles which he shared with some of his followers. Among those who lived there were Taisha Abelar (formerly Maryann Simko) and Florinda Donner-Grau (formerly Regine Thal). Like Castaneda, Taisha Abelar and Florinda Donner-Grau were students of anthropology at UCLA. Each went on to write books that explored the experience of being followers of Castaneda’s teachings from a feminist perspective. Cf. “Related Authors”

In 1974 his fourth book, Tales of Power, was published and chronicled the end of his apprenticeship under the tutelage of Matus. Castaneda continued to be popular with the reading public with subsequent publications that unfolded further aspects of his training with don Juan.

Later reviews were more critical, with several critics positing that the books were fabrications. Beginning in 1976, Richard de Mille published a series of criticisms that uncovered inconsistencies in Castaneda’s field notes, as well as several instances of apparent plagiarism. Later, anthropologists specializing in Yaqui Indian culture, such as Jane Holden Kelley, questioned the accuracy of Castaneda’s work. Other criticisms of Castaneda’s work include the total lack of Yaqui vocabulary or terms for any of his experiences, and his refusal to defend himself against the accusation that he received his PhD from UCLA through deception. Stephen C. Thomas notes that Muriel Thayer Painter, in her book With Good Heart: Yaqui Beliefs and Ceremonies in Pascua Village, gives examples of Yaqui vocabulary associated with spirituality: “morea”, an equivalent to the Spanish brujo; “saurino”, used to describe persons with the gift of divination; and “seataka”, or spiritual power, a word which is “fundamental to Yaqui thought and life.” Thomas further states:

Castaneda, along with Carol Tiggs, Florinda Donner-Grau and Taisha Abelar, created Cleargreen Incorporated in 1995. The organization’s stated purpose is “carrying out the instruction and publication of Tensegrity”. Tensegrity seminars, books, and other merchandise were sold through Cleargreen.

Castaneda died on April 27, 1998 in Los Angeles due to complications from hepatocellular cancer. There was no public service; Castaneda was cremated and the ashes were sent to Mexico. His death was unknown to the outside world until nearly two months later, on 19 June 1998, when an obituary entitled “A Hushed Death for Mystic Author Carlos Castaneda” by staff writer J. R. Moehringer appeared in the Los Angeles Times.

Around the time Castaneda died in April 1998, his companions Donner-Grau, Abelar and Patricia Partin informed friends they were leaving on a long journey. Amalia Marquez (also known as Talia Bey) and Tensegrity instructor Kylie Lundahl also left Los Angeles. Weeks later, Partin’s red Ford Escort was found abandoned in Death Valley.

Since his death, Carol Tiggs, a colleague of Castaneda, has spoken at workshops throughout the world, including at Ontario, California in 1998, Sochi, Russia in 2015 and Mérida, Yucatán in 2016. Tiggs had the longest association with Castaneda and is written about in some of his books. Today, she serves as a consultant for Cleargreen.

Luis Marquez, the brother of Talia Bey, went to police in 1999 over his sister’s disappearance, but was unable to convince them that it merited investigation.

In 2006, Partin’s sun-bleached skeleton was discovered by a pair of hikers in Death Valley’s Panamint Dunes area and was identified by DNA testing. The investigating authorities ruled Partin’s death as undetermined.