Change in the personality trait of self-confidence was studied in a group of children from the Berkeley Guidance Longitudinal study. Self-confidence was assessed at age 6 (n = 99) and again at age 10 (n = 97). Results indicated that a change in level of self-confidence was related to the use of defense mechanisms, as assessed from Thematic Apperception Test stories. A decrease in self-confidence was positively related to the use of the immature defense of denial and negatively related to the use of the relatively mature defense of identification. In contrast, an increase in self-confidence was unrelated to the use of defense mechanisms.