This study explored the anxiety, attitudes, and cognition of the need for aggression management among Taiwanese psychiatric nurses caring for psychiatric patients. Data were collected with self-report questionnaires from 180 psychiatric nurses in the acute wards of three large psychiatric centers in Taiwan. Results showed increased threat of cognitive appraisal of aggression, increased trait anxiety, and decreased positive attitudes toward aggression predicted higher levels of state anxiety. There were significantly higher levels of state anxiety among psychiatric nurses when patients exhibited verbal and physical aggression rather than just physical aggression. An important outcome of this study is the added understanding of cognitive appraisal, trait anxiety, and attitudes, that influence the anxiety of psychiatric nurses.