Until September 1923, his readings were not systematically recorded or preserved. However, an article published in the Birmingham Post-Herald on October 10, 1922, quotes Cayce as saying that he had given 8,056 readings as of that date and it is known that he gave approximately 13,000–14,000 readings after that date. A total of 14,306 are available at the A.R.E. Cayce headquarters in Virginia Beach and on an online, member-only section along with background information, correspondence, and follow-up documentation.

Other abilities that have been attributed to Cayce include astral projection, prophesying, mediumship, viewing the Akashic records or "Book of Life", and seeing auras. Cayce said he became interested in learning more about these subjects after he was informed about the content of his readings, which he reported that he never actually heard himself.

Cayce advocated some controversial ideas in his trance readings. In many trance sessions, he interpreted the history of life on Earth. One of Cayce's controversial claims was that of polygenism. According to Cayce, five human races (white, black, red, brown, and yellow) had been created separately but simultaneously on different parts of the Earth. Cayce also accepted the existence of aliens and Atlantis, and claimed that "the red race developed in Atlantis and its development was rapid." Another claim by Cayce was that "soul-entities" on Earth intermingled with animals to produce "things" such as giants that were as much as twelve feet tall.