The two groups did not differ on age, IQ, education, history of marriage, or family history, although marriage rates of both groups were well below the national average. Similarly, both groups had high rates of features that indicated family instability. HCMs more often victimized strangers. The results on the self-report psychological inventories, the Derogatis Sexual Functioning Inventory (DSFI) and the Buss-Durkee Hostility Inventory (BDHI), did not distinguish between the groups, although the DSFI revealed sexual inadequacy in both groups. The BDHI did not describe the groups as pathological. The Psychopathy Checklist-Revised Total Score, Factor 1, and Factor 2 described both groups as demonstrating high levels of psychopathy, with the HCM group in the 93rd and 82nd percentiles, respectively, compared to published norms for forensic patients. A greater proportion of HCMs suffered from antisocial personality disorders and paraphilias, especially sexual sadism. Over 53 percent of the HCMs and none of the CMs were comorbid for pedophilia and sexual sadism. Significantly more HCMs received three or more DSM III-R diagnoses. The phallometric assessments generally supported DSM diagnoses. The HCMs showed significantly higher levels of deviant arousal to pedophilic and adult assault stimuli. Police files revealed that, prior to the index offense, a significantly greater proportion of HCMs had been charged with, or convicted of, violent nonsexual and sexual offenses. The HCMs had been charged with, or convicted of, more than 2.5 times as many criminal charges than the CMs. A discriminant function analysis showed that two variables, Factor 1 of the PCL-R and the number of violent entries in the police records, correctly predicted 78.6 percent of the HCMs and 97.1 percent of the CMs. Implications for understanding homicidal child molesters and for future research are discussed. 5 tables and 66 references