Parkinson’s disease (PD) is a common neurodegenerative disorder affecting cognitive and motor functioning. The progressive nature of PD makes it a difficult disease for not only patients, but also their primary caregivers to cope with. There is evidence suggesting additional influences of social interactions to the psychological functioning of patients and caregivers in these patient- caregiver dyads, with the nature of perceived social interactions being associated to patient and caregiver outcomes. The current paper reports the relationship between supportive and unsupportive dyadic exchanges in 30 PD-MCI patients and their spousal caregivers, and how this was related to psychological functioning (psychological well-being and perceived relationship quality) of both spouses. Bivariate analyses suggested high levels of agreement in terms of how patients and caregivers perceived social interactions and their relationship quality, with patients and caregivers reporting high relationship quality and low levels of psychological distress. Furthermore, actor-partner-interdependence models (APIM), as predicted, revealed significant actor and partner effects between social interaction variables and psychological functioning, for both patients and caregivers, suggesting that social interactions from one spouse, influenced not only their own psychological functioning, but also their spouses’. These results further add to the general relationship and health literature that social interactions are related to psychological well-being and relationship quality in dyads adjusting to chronic illness. Furthermore, this is the first study to report dyadic interactions of this nature in PD-MCI patient-caregiver dyads, and warrants further longitudinal investigation to investigate the cause and effect of these associations.