In everyday life, we are often faced with the problem of judging who owns an object. The current experiments show that children and adults base ownership judgments on group stereotypes, which relate kinds of people to kinds of objects. Moreover, the experiments show that reliance on stereotypes can override another means by which people make ownership judgments--inferring ownership from first possession. Experiment 1 replicates previous findings in showing that children and adults are strongly biased to assume that the first person to possess an object is its owner, while also demonstrating that the first-possession bias shows specificity to ownership. Experiment 2 shows that preschoolers and adults used gender stereotypes to make ownership judgments, and they do this even when stereotypes conflict with first possession. Experiment 3 reports similar findings but with age stereotypes. These findings reveal that stereotypes are a powerful means for making ownership judgments.