Within the context of mental health disorders, the research examining the association between attachment and couples’ adjustment in general has been disappointingly lean. This includes consideration of the attachment representations of both members, as well as the dyadic attachment styles. This study analyzed the association between attachment and patient and partner’s individual and dyadic adjustment, as well as the associations between dyad attachment styles and patient and partner’s adjustment. The sample consisted of 54 couples, in which 1 member had been diagnosed with a mental health disorder (clinical groups), and 54 couples from the general population (control group). Participants completed the following self-report measures: Brief Symptom Inventory (BSI), the quality of life (QoL) questionnaire EUROHIS-QOL-8, the Revised Dyadic Adjustment Scale (RDAS), and the Experiences in Close Relationship-Short Form (ECR-SF). The results depict that couples from the clinical groups presented lower levels of QoL and dyadic adjustment and higher levels of depressive and anxious symptoms as compared to couples from the general population. Couples from the clinical groups also showed higher scores on attachment anxiety and avoidance. Women who possessed a clinical diagnosis, in particular reported higher scores in attachment anxiety whereas men with a clinical diagnosis were found to engage in attachment avoidance. Regarding both dyadic attachment styles, dyads in which the 2 partners were insecurely attached had significantly poorer individual and dyadic adjustment compared with dyads in which both partners were secure. The clinical implications of the results are considered, as well as some key directives for future research.