The aim of this paper is to show that there is a reciprocal dependency relationship between social cognition and social ontology. It is argued that, on the one hand, the existence conditions of socially meaningful objects and of social groups are about subjects’ social cognitive processes and interactive patterns and, on the other hand, social cognitive processes and interactive patterns are modulated by socially meaningful objects and social groups. I proceed from a historically informed distinction between social ontologies – between (...) what might be called constructivist and emergentist theories of social reality. I then distinguish three theories of social cognition, theory-theory, simulation theory, and interaction theory, and argue that the first distinction and the latter map onto each other. Finally I argue that the reciprocal dependency between social ontology and social cognition can be justifiably though of as causal in Di Paolo et. al.’s (2010) sense of “downward” or “circular” causation. It is concluded that the dependency between social ontology and social cognition pertain to both a methodological and a phenomenal level. First, research on social ontology depends on research on social cognition; and, secondly, social phenomena, involving socially meaningful objects and groups, influence social cognitive processes and interaction, which in turn influence social phenomena. (shrink)