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. Average opportunity cost per caregiver will likely increase by 8-20 percent and per US resident by 54-72 percent. Future policy action could benefit from accounting fully for the economic costs in addition to the benefits of unpaid caregiving, which would help better define the scope and size of programs needed to support caregivers.