Patient defensive behavior and therapist addressing defense (TAD) was studied over the course of two brief dynamic psychotherapies in twenty-eight patients with personality disorders, primarily of the Axis II Cluster C variety. Three levels of patient defense were coded: immature, intermediate, and mature. Results indicate a significant decrease in the frequency of intermediate defensive behavior across psychotherapy which is not related to patient outcome. However, there is a positive relationship between the frequency of immature defenses in the first quartile of treatment and outcome at termination. Further, there is a significant correlation between patient defensive behavior and the therapist addressing this behavior, as well as a decrease in immature and intermediate defenses which correlates with the frequency of the therapist addressing these behaviors earlier in treatment. Finally, the frequency of TAD is significantly correlated with patient outcome.