Background: Ovarian cancer is commonly diagnosed at a late stage of illness, raising significant challenges to health-related quality of life (QOL). Increasingly, cancer is conceptualized as an interpersonal stressor that significantly impacts patients as well as their spouses. It has been suggested that adult attachment significantly impacts health outcomes by way of dyadic processes. The present study used the actor partner interdependence model (APIM) to examine the dyadic effects of adult attachment and dyadic coping on QOL, and whether dyadic coping mediated the associations between attachment and QOL. Methods: Couples (N=106) facing ovarian cancer were recruited from a comprehensive cancer centre in Toronto, ON. Attachment was measured by the Experiences in Close Relationships Scale – Revised, dyadic coping was measured by the Dyadic Coping Inventory, and QOL was measured by the Functional Assessment of Cancer Treatment. APIM analyses evaluated within person and cross-dyadic effects. Role (patients compared with spouses) was examined as a moderator. Results: There were significant within person effects of anxious attachment on physical, social, emotional, and functional QOL. There were also significant within person effects of avoidant attachment on social, emotional, and functional QOL. Positive and negative dyadic coping demonstrated significant within person effects on social and functional QOL. There were no significant cross-dyadic effects nor was there evidence of moderation by role. The within person association between avoidant attachment and social QOL was significantly mediated by positive dyadic coping. The within person association between anxious attachment and social QOL was significantly mediated by positive and negative dyadic coping. Additionally, there was a significant indirect cross-dyadic effect, such that greater anxious attachment reported by one partner was associated with less positive dyadic coping and subsequently less social QOL reported by the other partner. Discussion: Adult attachment and coping as a couple are important considerations in understanding QOL among both patients and spouses. Intervention strategies to address attachment, and the behavioural system associated with attachment, such as dyadic coping, may be useful in addressing impaired individual well-being. Future studies should consider additional dyadic processes that may account for the negative effects of attachment on QOL such as intimacy.