The findings indicate that sadistic sexual offenders (offenders who derive sexual pleasure from controlling, torturing, and humiliating their victims) were exposed to physical and psychological violence as well as alcohol abuse during childhood and adolescence. A large percentage were also victims of physical and sexual violence. Sadists were more likely than nonsadist sex offenders to have experienced psychological violence (e.g., humiliation) during their childhoods and in adolescence. This form of victimization was compatible with the development of an avoidant personality disorder, which is characterized by a fear of being humiliated, criticized, or rejected by others. The sadistic sex offenders were also distinguished from nonsadistic sex offenders by their low self-esteem and pronounced social isolation during childhood and adolescence. Sadists' adolescence was dominated by sexual activities that distinguished them from nonsadists. They consumed pornography and turned to violent sexual fantasies during masturbation. The phallometric assessments showed that the sadistic sexual aggressors preferred rape (humiliation and physical violence). The study sample consisted of 141 extrafamilial sexual aggressors against women, including 71 percent of the sexual murderers of women incarcerated in Quebec in 1999. Two sadism scales of the MTC-R-3 (Knight & Prentky, 1990) were used to classify subjects as sexual sadists and nonsadists. Phallometric assessments used French translations of the stimuli reported by Abel et al. (1978). 4 tables