Objectives: To investigate informal caregivers' psychological well-being and predicted increase in psychological well-being, when caring for persons with dementia (PwDs) living at home, related to caregiver, PwD and formal care (FC) factors.; Method: A cohort study at baseline and 3 months' follow-up in eight European countries. Caregivers included (n = 1223) were caring for PwDs aged ≥ 65 years at home. Data on caregivers, PwDs and FC were collected using standardized instruments.