Over a 6-year period, all patients voluntarily attending the Kingston Sexual Offenders' Clinic who admitted to having engaged in other forceful acts with adult females or sex with children and who attended at least five evaluation sessions were interviewed about their use of hardcore pornography. This sample consisted of 89 subjects; the control group consisted of 24 white males with no history of sexual offending but whose ages, intelligence, and socioeconomic class approximated those of the child molesters. As adults, the child molesters and rapists made more use of hardcore pornography than did either the nonoffenders or the incest offenders. Similarly, the child molesters and rapists were more likely to entertain fantasies during masturbatory activities than were the incest offenders or the nonoffenders. Slightly more than one-third of the child molesters and rapists claimed to have been incited to commit an offense by exposure to one or the other type of the sexual materials specified in the study. Implications of these findings are drawn for the prevention and treatment of sex offenders. 2 tables, 13 references.