The purpose of this study was to provide an overview of caregiver prevalence and characteristics and to estimate the impact of caregiving on health care utilization and expenditures among AARP® Medicare Supplement insureds to inform caregiver intervention strategies. A subgroup with live-in partners was used to investigate the additional effect of live-in health status on caregiver health. Multivariate regression models were utilized to determine caregivers' characteristics and associated impacts on their health care utilization and expenditures.