This paper pursues a naturalist endeavor in social ontology by arguing that the Beliefs-Rules-Equilibrium account of institutions can help to advance the debate over the nature of social kinds. This account of institutions emerges from a growing number of works in economics that use game theory to study the role and the functioning of institutions in human societies. I intend to show how recent developments in the economic analysis of rules and institutions can help solve issues that are generally considered constitutive of any ontological inquiry. I argue that the Beliefs-Rules-Equilibrium account of institutions can contribute to advancing the debate on an issue of particular importance, regarding the specific form of dependence character...