It has long been argued that ownership depends upon social groups' establishing and adhering to rights such as the right to use and to exclude others from using one's own property. The authors consider the application of such rights in the interactions of young peers and siblings, and the extent to which parents support their children in establishing and maintaining the entitlement of owners. They show that children, but not their parents, give priority to ownership in settling property disputes, and argue that diverging models of children's relationships account for these differing perspectives of children and parents. (Contains 1 figure.)