Laboratory research on rape has examined how the context of the offense and characteristics of the victim influence responsibility ascriptions. The present research examined the influence of the perpetrator's personality on such attributions. This study distinguished between evaluative (general likability) and descriptive (aggressiveness) components of the perpetrator's personality and assessed the effect of each on subjects' confidence of the perpetrator's guilt or innocence for an alleged acquaintance rape. Results showed that subjects were more confident in the defendant's guilt when he was described by cohorts as generally dislikable versus likable, and as aggressive versus unaggressive. Assessments of academic punishment and legal responsibility generally paralleled these findings. Females were more confident in the defendant's guilt, and this was particularly true when the defendant was described as aggressive.