Researchers have demonstrated that people with mental retardation have deficits in processing facial expressions of emotion. The ability of 18 aggressive and 21 nonaggressive men with borderline to moderate mental retardation to label and discriminate facial expressions was investigated. Although results did not support the hypothesis that aggressive participants would have greater difficulty with emotion labeling and discrimination compared to their nonaggressive peers, they do suggest that aggressive individuals may have a negative emotional bias for facial expressions that are ambiguous to them. Results further suggest that adults with mental retardation are not able to label the six basic facial expressions with equivalent accuracy and provide evidence for the salience of the mouth when labeling and discriminating facial expressions.