People sometimes disagree about who owns which objects, and these ownership dilemmas can lead to costly disputes. We investigate the cognitive mechanisms underlying people's judgments about finder versus landowner cases, in which a person finds an object on someone else's land. We test psychological hypotheses motivated directly by three major principles that govern these cases in the law. The results show that people are more likely to favor the finder when the object is in a public space compared to a private space. We find mixed support for the hypothesis that people are less likely to favor a finder who is employed by the landowner. Last, we find no support for the hypothesis that people are more likely to favor finders for objects located above ground compared to below ground. We discuss implications for psychological theories of ownership and potential applications to property law.