Background: Being an informal carer of a person with dementia (PwD) can have a negative effect on the carer’s health and quality of life, and spouse carers have been found to be especially vulnerable. Yet relatively little is known about the care provided and support received by spouse carers. This study compares spouse carers to other informal carers of PwDs regarding their care provision, the support received and the psychosocial impact of care. Methods: The study was a cross-sectional questionnaire-based survey of a stratified random sample of the Swedish population aged 18 or over. The questionnaire explored how much care the respondent provided, the support received, and the psychosocial impact of providing care. Of 30,009 people sampled, 11,168 (37.7 %) responded, of whom 330 (2.95 %) were informal carers of a PwD. Results: In comparison to non-spouse carers, spouse carers provided more care more frequently, did so with less support from family or the local authority, while more frequently experiencing negative impacts on their social life and psychological and physical health. Spouse carers also received more carer support and more frequently experienced a closeness in their relationship with the care-recipient. Conclusions: Spouse carers of PwD differed from non-spouse carers on virtually all aspects of their care situation. Policy and practice must be more sensitive to how the carer-care-recipient relationship shapes the experience of care, so that support is based on an understanding of the individual carer’s actual needs and preferences rather than on preconceptions drawn from a generalised support model.