Older Americans living in the community who need help with functional limitations overwhelmingly rely on unpaid care, which is often provided by working-age family members. This study assessed the impact of unpaid family caregiving on the likelihood of working and hours worked for caregivers and calculated the related cost of forgone earnings in 2013 and 2050. The current economic cost is about $67 billion, which by midcentury will likely double to $132-$147 billion, fueled primarily by the growth of the disabled older population and the increased share of better-educated caregivers.