The pathophysiological consequences of caregiving have not been fully elucidated. We evaluated how caregiving, stress, and caregiver strain were associated with shorter relative telomere length (RTL), a marker of cellular aging. Caregivers (n = 240) and some noncaregivers (n = 98) in the 2008–2010 Survey of the Health of Wisconsin, comprising a representative sample of Wisconsin adults aged 21–74 years, reported their sociodemographic, health, and psychological characteristics. RTL was assayed from blood or saliva samples.