Compared to multiple perpetrators, individual perpetrators were more likely to be older and to target female victims, and their homicides were more likely to contain reactive, sexual, and sadistic elements. Multi-perpetrator homicides more likely involved younger offenders, male victims, and instrumental motives. Psychopathic offenders were likely to act alone in committing sexual homicides and to involve an accomplice in other types of murders, however, they typically committed gratuitous violence against women regardless of whether they acted alone or with someone. Collectively, the findings may be of assistance to criminal investigators when attempting to delineate the likely number of perpetrators involved in the commission of a homicide or when a suspect high in psychopathic traits may have played a role. Little is known about the characteristics of homicides committed by more than one perpetrator. This study was an exploratory analysis of crime, victim, and perpetrator characteristics differentiating individual and multi-perpetrator homicides. It also examined relationships with psychopathy. Participants in the study consisted of 125 male offenders convicted of a homicide and incarcerated in 1 of 2 Canadian Federal correctional facilities. Tables, figures, and references