Ownership is often viewed as demarcating who can use resources and who is restricted from using them. For example, legal and philosophical accounts of ownership specify how property can be legitimately acquired, and which rights ownership confers. And psychological research shows that young children and adults recognize many ways of establishing ownership and view owners as entitled to decide what happens to their property. All of this is consistent with the idea that assigning individuals ownership rights chiefly functions to ensure that efforts to gain and control resources remain efficient. In this talk, I will review the developmental research that supports this conception of ownership. However, I will then review several lines of research which together show that ownership serves other functions. This includes work showing that children and adults alike sometimes find it acceptable to interfere with others’ property when this benefits the owner, work showing that they hold owners responsible when property causes harm, and work showing that adults use attributions of ownership to hold others accountable.