Cancer diagnosis affects the psychological well-being of both patients and their partners, and effective coping has been suggested to be a conjoint process of mutual support. Ninety-four married women with early stage cancer and their partners were randomly assigned to couples-based coping training (CanCOPE), individual coping training for the woman, or a medical education control. Couples' observed support communication and self-reported psychological distress, coping effort, and sexual adjustment were assessed at diagnosis, after cancer surgery, and at 6- and 12-month follow-ups. CanCOPE produced significant improvements in couples' supportive communication, reduced psychological distress and coping effort, and improved sexual adjustment. Training in couples rather than individual coping was more effective in facilitating adaptation to cancer.