Although people take care of their own possessions, they also engage in stewardship and take care of things they do not own. Here, we examined what young children infer when they observe stewardship behavior of an object. Through four experiments on predominantly middle-class Canadian children (total N = 350, 168 girls and 182 boys from a predominantly White and middle-class region), we found that children as young as 4 or 5 infer feelings of ownership from stewardship behaviors and distinguish between psychological and legal ownership. They also understand that psychological and legal ownership are independent as one can exist without the other, and children as young as 3 may link stewardship with welfare concerns. We also suggest that while stewardship has been shown to be a consequence of psychological ownership, it is also likely to be an antecedent. As future stewards of our resources, young children's understanding of the link between psychological ownership and stewardship links directly to sustainability concerns. We contribute theoretically both to the child development and psychological ownership literatures.