Masson argued in The Assault on Truth (1984) that psychoanalysis founder Sigmund Freud wrongly abandoned his early belief that his patients' symptoms stemmed from real childhood sexual abuse.

He sued journalist Janet Malcolm for libel over her portrayal of him, and the case reached the U.S. Supreme Court in 1991.

• He later wrote best-selling books on animal emotions, including When Elephants Weep (1995).