The relationship betweendefense mechanism use, observed behavior, and affect was investigated in a sample of 91 youngadults. Defense mechanisms were assessed using Cramer's (1991a) Defense MechanismManual for TAT stories; behavior was based on observer Q-sort ratings (Block, 1978). Thefindings show that men and women who rely on the immature defense of denial at age 23 showmultiple signs of behavioral immaturity, as well as anxiety. In contrast, extensive use of projectionwas related to a suspicious, hyperalert personality style, including anxiety and depression, in men,but to a sociable, nonwary, nondepressed style in women. The use of the mature defense ofidentification, by women, was related to behavior characterized by maturity, social competence,and the absence of depressive symptoms.