Castaneda wrote twelve books and several academic articles detailing his experiences with the Yaqui Indians indigenous to parts of Central Mexico. His first three books, The Teachings of don Juan: a Yaqui way of knowledge, A Separate Reality and Journey to Ixtlan were written while Castaneda was an anthropology student at UCLA. Castaneda wrote these books as if they were his research log describing his apprenticeship with a traditional shaman identified as don Juan Matus. Castaneda was awarded his bachelor's and doctoral degrees for the work described in these books.

His work has been criticized by academics, and is seen as highly suspect in terms of strict anthropological fieldwork. Many have tried to corroborate Castaneda's stories with his own personal history and that of his fellow apprentices. Contradictory evidence suggests Castaneda wrote in the traditional allegorical style of the storyteller (ethnopoetics) common to many native Indian cultures.

Perhaps the most highly contested aspects of his work are the descriptions of the use of psychotropic plants as a means to induce altered states of awareness. In Castaneda's first two books, he describes the Yaqui way of knowledge requiring the use of powerful indigenous plants, such as peyote and datura. In his third book, Journey to Ixtlan, he reverses his emphasis on 'power plants'. He states that don Juan used them on Castaneda to demonstrate that experiences outside those known in day-to-day life are real and tangible.

Castaneda later disavowed all use of drugs for these purposes, stating they could inalterably damage the luminous ball (energy body) or physical body.

Castaneda was a popular enough phenomenon for Time magazine to do a cover article on Castaneda on March 5, 1973 (Vol. 101 No. 10) that was five or six pages long.

His fourth book, Tales of Power, ended with Castaneda leaping off a cliff marking his graduation from disciple to man of knowledge (actually a leap from the tonal into the unknown). Some writers thought this must necessarily mark the end of his series. They were very surprised to see he continued to produce more books. Despite an increasingly critical reception Castaneda continued to be very popular with the reading public. Twelve books by Castaneda have been published, and three videos released.

In 1997 Castaneda launched a lawsuit against his ex-wife, Margaret Runyon Castaneda, over her book, A Magical Journey with Carlos Castaneda; but this was dropped when Castaneda died.

Castaneda purportedly died on April 27, 1998 from liver cancer in Los Angeles. Little is known about his death. There was no public service, Castaneda was apparently cremated and the ashes were sent to Mexico.

The mystery surrounding the facts of Casteneda's life and death can be seen through the lens of the Toltec teachings as an impeccable effort on his part to erase his personal history.

The nine popular works (as opposed to the academic or scholarly works) of Carlos Castaneda are organized into three sets of three, where each set corresponds to a Toltec mastery: the mastery of awareness, the mastery of transformation, and the mastery of intent. For each mastery there is also a compendium that describes essential teachings from the overall body of work. The three compendiums were published posthumously.

Each mastery is described in four works, three works presented in story form and one work compiled as a cross-set reference:

The Mastery of Awareness

The Teachings of Don Juan: A Yaqui Way of Knowledge (1968) A Separate Reality: Further Conversations with Don Juan (1971) Journey to Ixtlan: The Lessons of Don Juan (1972) Compendium - Magical Passes: The Practical Wisdom of the Shamans of Ancient Mexico (1998) The Mastery of Transformation

Tales of Power (1975) The Second Ring of Power (1977) The Eagle's Gift (1981) Compendium - The Active Side of Infinity (1999) The Mastery of Intent

The Fire from Within (1984) The Power of Silence: Further Lessons of Don Juan (1987) The Art of Dreaming (1993) Compendium - The Wheel Of Time : The Shamans Of Mexico (2000) The following list generally defines each mastery:

Mastery of Awareness - The Mastery of Awareness entails the re-emphasis of awareness from the world of the tonal (every day objects) to the world of the nagual (spirit). During this stage of development the warrior-traveler endeavors to minimize self importance and gather energy. First and foremost, the student is encouraged to take action and assume responsibility for his or her life. Mastery of Transformation - During The Mastery of Transformation the warrior-traveler endeavors to cleanse and retrieve energy and to hone his only link to spirit, the intuition. The warrior-traveler becomes impeccable by empirically testing this connection and eventually banishing all doubts, accepting his or her fate, and committing to follow a path with heart. Mastery of Intent - Once the warrior-traveler has accumulated enough surplus energy, enough personal power, the dormant second attention is activated. Dreaming becomes possible. The warrior-traveler maintains impeccability, walks the path with heart, and waits for an opening to freedom. Castaneda's books can be read as a philosophical/pragmatical text that express a world view by which a person can live one's life. There is a movement world-wide of practitioners of this philosophy, applying Castaneda's published ideas either independently or through consultation with Castaneda's associates.

According to Castaneda, the most significant facts in a person's life are his possession of a dormant awareness and the possiblity that one may keep this awareness after death. The primary goal of a Toltec "Warrior" is the continuation of his awareness after bodily death: to "dart past the Eagle and be free", in the words of the tradition, where the Eagle is the force which consumes the awareness of all living beings.

To cheat death in this way requires all of the discipline and procedures that constitute the Warrior's way of life. These practices are devised to maximise the Warrior's personal power, or experience. The condition maintaining personal power is known as "impeccability".

Sufficient personal power leads to the mastery of intent, chiefly the controlled movement of what is known as the "assemblage point". This is an artifact of the tradition's description of another world underlying what we perceive as ordinary reality. In this description men are glowing cocoons of awareness inhabiting a universe consisting of the Eagle's "emanations", described euphemistically as all-pervading filaments of light.

Humans' cocoons are intersected throughout by these filaments, producing perception, but they filter our perceptions by concentrating on only a small bundle. The assemblage point is the focusing lens which selects from the emanations. In its accustomed position, the assemblage point produces what humans perceive as everyday, 'normal' reality. Movement of the assemblage point permits perception of the world in different ways; small movements lead to small changes in perception and large movements to radical changes. For example, dreaming is presented as the result of a movement of the assemblage point; "power plants" such as Peyote, used in the early stages of Castaneda's apprenticeship, produce powerfully altered states of mind through such movement.

Castaneda describes complex and bizarre worlds experienced through the controlled movement of the assemblage point in dreaming; his premise is that the world of the dreams of a warrior is no less real than the world of daily life. This follows logically from the description of both worlds as being simply the result of positions of the assemblage point. He depicts complex interactions with unearthly beings in dream worlds and describes his fear of being physically trapped by these malicious but charismatic beings.

Amongst the various practices of a warrior, Tensegrity, a series of meditative stretching and posing techniques, is introduced in Castaneda's tenth work, Magical Passes. The term is borrowed from architecture—"tensional integrity". Tensegrity is promoted by Cleargreen, Inc., a company founded in the 1990s, closely affiliated with Castaneda, which runs workshops and sells various materials relating to Castaneda's work. There are many individual and group practitioners around the world. Tensegrity and much of Castaneda's other work are the subject of a variety of recurring disputes.