With reference to Bruno Latour and Gabriel Tarde, Daniel Falb sketches a process-oriented conception of collectivities, at the heart of which stand populations and networks in their shifting constitutions. In a novel founding of social ontology, collectivities are posited as »process-objects« , which hold their place in the world exclusively through performative repetition. This interdisciplinary approach elucidates - both in their logics and in their relation to one another - the philosophical problems of universals, the scientific-historical question of the foundation of static stability, and the sociological topic of the materiality of actor-networks.