This thesis explored caregiver responses to persons with dementia (PWD) in association with psychological outcomes in both caregivers and PWD, using a variety of methods, including a systematic review, a naturalistic study using the Expressed Emotion (EE) methodology with cross-sectional and longitudinal elements, and a mediation analysis. The systematic review (Paper 1; Chapter 2) showed that caregiver factors, such as interpersonal relationships, responses and beliefs, are associated with wellbeing outcomes in caregivers of PWD. Methodological limitations of previous work and gaps in research were identified from the review and the subsequent empirical papers presented attempt to address these. The first empirical study (Paper 2; Chapter 5) utilised the EE framework to explore the impact of key aspects of interpersonal relationships on caregiver outcomes. A cross-sectional relationship was found between caregiver EE, burden and psychological distress. Furthermore, when controlling for baseline measures, high-EE caregivers showed increased levels of burden and distress over time. Paper 3 (Chapter 6) explored the influence of caregiver EE on psychological wellbeing in PWD. Interestingly, low-EE appeared to have a protective effect, as PWD with low-EE caregivers experienced a reduction in depression and anxiety over 6 months, whereas those with high-EE caregivers maintained baseline levels of depression and anxiety. Decomposing EE into its constituent constructs, caregiver emotional over involvement predicted greater levels of PWD anxiety and critical comments predicted greater levels of PWD depression. Paper 4 (Chapter 7) examined the relationship between caregiver distress, caregiver criticism and psychological wellbeing in PWD. There were cross-sectional and longitudinal relationships between caregiver distress, critical comments, anxiety in PWD and depression in PWD. Furthermore, baseline caregiver distress was found to be predictive of poorer quality of life in PWD at 6 month follow-up, and this relationship was mediated by the number of caregiver critical comments. Taken together, the findings presented within this thesis provide evidence for the impact of caregiver factors on psychological outcomes in both caregivers and PWD. Finally, the results suggest that the development of caregiver-focused interventions may be beneficial for both PWD and caregiver outcomes.