Reports on an empirical study of defense mechanisms in 60 psychiatric inpatients. Eight defenses were studied in the context of a 2-stage model of suicidal & violent behavior. Results showed that use of regression as a defense differentiated suicidal from nonsuicidal patients, & use of displacement differentiated violent from nonviolent patients. Repression tended to turn aggression inward, & projection & denial turned aggression outward. (43 ref)