The expected increasing demand for informal care in aging societies underscores the importance of understanding the psychological implications of caregiving. This study explores the effect of providing regular help with personal care to a partner on different aspects of psychological well-being. We use cross-sectional data from the Norwegian Life Course, Ageing and Generation study (n. ~15,000; age 40-84) and two-wave panel data from the Norwegian study on Life Course, Ageing and Generation (n. ~ 3000; age 40-84). To separate the effects of providing care from those of the partner’s disability, caregivers are contrasted with non-caregivers with both disabled and nondisabled partners. We separate outcomes into cognitive well-being (life satisfaction), psychological functioning (self-esteem, mastery), and affective well-being (happiness, depression, loneliness). Findings show that caregiving has important cross-sectional and longitudinal detrimental psychological effects. These effects are fairly consistent across all aspects of well-being, demonstrating that caregiving has a broad-based negative impact. Among women, however, these effects are similar to if not weaker than the effects of a partner’s disability. Caregiving effects are constant by age, education, and employment status, but stronger among caregivers with health problems. Providing personal care to a partner is associated with marked adverse psychological effects for men and women irrespective of age and socio-economic status. Hence, no socio-demographic group is immune from caregiving stress, so programs should be targeted generally. The results also suggest that the health needs of caregivers demand more attention.