Dyadic adjustment and coping styles have been shown to predict levels of psychological distress following cancer diagnoses. This study examined the relationship between coping and distress in couples faced with prostate cancer, considering dyadic functioning as a third variable that potentially moderated or mediated the relationship. To investigate its influence on the success of patients' and spouses' coping efforts, both moderational and mediational models were tested using couples' composite dyadic adjustment scores. Only the moderational model was supported for patients: dyadic strength moderated the effects of avoidant coping and intrusive thinking on mood disturbance. Despite maladaptive coping, patients that were members of stronger dyads reported less distress than those in more dysfunctional relationships. Findings suggest that the relationship between coping and distress depends on the quality of dyadic functioning. Being part of a strong dyad may serve as a buffering factor, implying the need for psychosocial intervention for couples in maladjusted relationships.