In his recent Immaterialism, Graham Harman develops a theory of social objects based on his object-oriented ontology. Whereas some of the more mainstream theories in the humanities would dissolve such objects into their material constituents or their various effects on others, object-oriented social theory theorizes them as inert, resilient entities with a private reality that exceeds their components and actions. Harman’s theory focuses on what social entities are qua objects, and consequently says little about their specificity as social objects. A (...) more complete social theory would also outline how human existence is to be understood in relation to a social world comprised of discrete and inert entities, as opposed to, for example, far more continuous material fields or networks of associations. We argue that an unexpected yet solid candidate for such an extension of object-oriented social theory already exists in Jean-Paul Sartre’s theory of practico-inert being and group formation. We first outline Harman’s and Sartre’s respective ontologies of social objects, and then discuss how their many complementarities make the latter a suitable extension of the former. (shrink)