This study explores differences between group and lone sexual assaults, using a framework of interpersonal dimensions of dominanceÁsubmission and cooperationÁhostility (Alison & Stein, Journal of Forensic Psychiatry, 12, 515Á538, 2001). From archival sources, 120 cases (60 group and 60 lone offender assaults) were content analysed for offender, victim and context variables. A number of behavioural characteristics were found to differ between group and lone rape. Specifically, more hostile interactions were involved in group rape, including increased violence. Additionally, (pseudo-) submissive offender behaviour was more frequent in lone assaults, including the offender's use of a confidence approach and associated greater victim dominance. The psychological implications are discussed, with particular reference to the circumplex dimensions and principles, and how these can inform the treatment of both offenders and their victims.