What are the theoretical issues that social ontology deals with? What are its historical origins? What are its relations to general ontology and philosophy? In order to answer these questions, Andina offers a presentation of contemporary ontology starting from its historical origins and showing how the discipline became what it is—namely, the study of the constitutive elements of social reality—describing its structure and identifying its underlying normativity. In addition to reconstructing the theoretical foundations of the discipline, the chapter identifies and discusses its basic notions: covenants, promises, relationships, transgenerationality, institutions, states and meta-states.