This chapter has four goals. First, it seeks to define natural resources, differentiating them from other goods with which a theory of justice might be concerned. Second, it discusses the diversity of natural resources, and highlights the ways in which this diversity might become matter for a theory of resource justice. Third, it clarifies the focus of a theory of natural resource justice, and engages with some competing views about what the focus of such a theory should be. Fourth, it provides a conceptual framework for thinking about issues of resource justice, by sketching an account of the most important rights we might have over natural resources.