After two centuries of demographic change, societies of European origin face a new reality of aging populations and heightened competition for resources between young and old. Research on the history of the family adds important perspectives on our current problems. In northwestern Europe, transfers of resources to the young and old were constrained by an unusual marriage and household formation system. The transition to small families increased downward intergenerational transfers (parents to children), and compensating upward transfers now take place outside the family. The growing independence of the elderly in the twentieth century is based on earlier investments in children. The members of each generation profit from the investments their parents make in them and the investments they make in the children of others.