Historical and recent developments in legal economic analysis of adoption the United States reveal changing supply and demand of children and the emergence of submarkets for adoption through agencies (public or private) and independent adoptions. Curent legal rules against baby-selling and adoption agency practices mask the existence of adoption markets by banning payments to birth parents yet exempting payments to agencies and other adoption professionals. Economic proposals seek to narrow gaps between supply and demand by creating incentives (or removing disincentives) through substitutes, subsidies, and reduced transactions costs. These solutions could prevent a good number of would-be parents from remaining childless, provide homes for many children who currently languish in foster care or group homes, and better recognize the costs that adoption imposes on birth parents.