Cancer diagnosis and treatment affects the psychological wellbeing of both patients and their partners. Couples who adapt well to their cancer experience are said to engage in “couple-coping”, a process of conjoint coping and mutual support that forges a shared approach to managing the stressors they encounter. However, most psycho-oncology interventions focus on assisting the patients alone to cope with cancer. Little is known about how to help couples develop a unified stand against cancer, or whether couples who cope as a team are more successful in re-claiming their lives after cancer than patients who wage a solo battle. The present study examined the efficacy of promoting couple coping compared to enhancing the patients’ coping alone. Ninety-four married women with early stage cancer and their partners were randomly assigned to couple-based coping and support 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. Relative to the other conditions, CanCOPE produced significant improvements in couples’ supportive communication, reduced psychological distress and coping effort, and improved sexual adjustment. Training in couple coping rather than individual coping was more effective in facilitating adaptation to cancer. The findings have practical implications for the delivery of psychological support services to women with cancer, as well as broader theoretical implications for the way models of stress and coping have traditionally been conceptualised.