This study examined the relationships between adult attachment, cognitive appraisal, and university students' behavioral and emotional reactions to infidelity situations in romantic relationships. Results based on 173 university students suggested that both attachment and cognitive appraisals significantly predicted distinct types of infidelity reactions and that participants' cognitive appraisal mediated the effects of attachment on behavioral and emotional reactions. Counseling applications for university counselors are discussed on the basis of attachment perspectives and cognitive appraisal models. (Contains 2 tables.)