Purpose: Unpaid care is an important source of support of people with long-term conditions. Interdependence of carers’ and care recipients’ quality of life would be expected due to the relational nature of caregiving. This study aims to explore interdependence of quality of life in carer/care-recipient dyads, especially in relation to mutual interdependence due to social feedback in the caregiving relationship and also the partner effects of one partner’s experience of long-term care support on the other’s outcomes.