Many studies of intergroup relations have examined the effects of group identity on various types of intergroup cognition and behavior. However, few studies have focused on the perceived group identity of outgroup members. This study examined the effects of perceptions of outgroup identity on anticipated rejection by an outgroup. In Study 1, we administered a questionnaire pertaining to 30 social groups to Japanese undergraduate and vocational students. The collective images and intra-individual processes relating to perceived outgroup identity were investigated by applying correlation analysis and multilevel structural equation modeling. In Study 2, we conducted an experiment in which we manipulated the participants' perceptions of relative levels of outgroup members' identity. Both studies demonstrated, as predicted, that people anticipated rejection by strongly identified outgroup members more than by weakly identified outgroup members. Furthermore, in Study 2, anticipated same-group favoritism mediated the relationship between the manipulation of perceived outgroup identity and anticipated rejection. These findings suggest the important role of perceived outgroup identity in intergroup cognition.