This study examined the direct and indirect relationships between caring for a person with dementia and caregiver health. A conceptual model of the caregiver stress process considered informal caregiver characteristics, sources of caregiver stress, and the influence of informal and formal support on the well-being of the caregivers of persons with dementia. Structural equation modelling was used to test specific hypotheses in a sample of 327 caregivers of people with dementia who were living in the community, as part of the first wave of the Canadian Study of Health and Aging. Our findings show that the negative impact of the increasing disability of the care recipient on the psychological well-being of the caregiver was mediated mostly by the use of informal support systems and marginally by the use of formal support systems. The use of informal support by caregivers was associated with a decreased use of formal supports. The relationship between caregiver characteristics and their psychological health was mediated by the use of formal support but not by the use of informal support systems.