This study examined the effects of therapist competence in assigning homework on the outcome of CT (cognitive therapy) in patients with Cluster C personality disorders. 25 participants underwent 40 weekly, 50 minute, CT sessions that followed the Beck and Freeman treatment manual for personality disorders. The six treating therapists employed three primary techniques: guided imagery, homework assignments that led the patients to try new adaptive responses, and cognitive, behavioral, and emotion-focused techniques to develop new, more adaptive beliefs to replace the pathological beliefs. The researchers used the Global Severity Index of the Symptom Checklist 90 Revised to measure symptom distress, the mean scores of the 127-item version of the Inventory of Interpersonal Problems to evaluate interpersonal problems, and the Millon Clinical Multi-axial Inventory to measure personality pathology, as prescribed by the personality disorder scales of avoidant, dependent-submissive, compulsive-conforming, and passive-aggressive. Additionally, they tracked initial symptom improvement after the fourth session using the Helping Alliance Questionnaire. The researchers measured therapist competence in assigning, monitoring, and reviewing homework with the homework assignment subscale of the Cognitive Therapy Scale. This rating is based on the extent to which the therapist reviewed previous homework and summarized progress and conclusions, provided rationale for the assignment and the intended goals, tailored the assignment to the patient’s specific needs, and asked for reactions and feedback from the patient. The researchers also measured therapist competence in agenda setting. Higher ratings of therapist competence in assigning homework were related to statistically significant improved outcomes on all measures at mid and post-treatment. Therapist competence in agenda setting, however, did not predict treatment outcome at either time. This study is the first to examine the relationship between therapist competence in assigning homework and treatment outcome in patients with Cluster C personality disorders, and the first to find that higher ratings of therapist competence in assigning homework predict greater positive change in symptoms, interpersonal problems, and Cluster C personality pathology.