Four relatively independent emotion-regulation constructs (suppression of negative affect, restraint, repression, and emotional self-efficacy) were tested as outcomes in a randomized trial of supportive-expressive group therapy for women with metastatic breast cancer. Results indicate that report of suppression of negative affect decreased and restraint of aggressive, inconsiderate, impulsive, and irresponsible behavior increased in the treatment group as compared with controls over 1 year in the group. Groups did not differ over time on repression or emotional self-efficacy. This study provides evidence that emotion-focused therapy can help women with advanced breast cancer to become more expressive without becoming more hostile. Even though these aspects of emotion-regulation appear trait-like within the control group, significant change was observed with treatment.