In this paper, I argue that Slavic derivational morphology reflects two modes of collectivity. In particular, I examine two types of derived collectives exemplified by the Polish nouns such as `kwiecie' (`clump(s) of flowers, blossom') and `duchowieństwo' (`collective(s) of priests, clergy') and argue that they both denote properties of clusters, i.e., structured configurations of entities. Spatial collectives are predicates true of spatial clusters, i.e., topological arrangements of objects in physical space, whereas social collectives are predicates true of social clusters, i.e., abstract configurations of roles individuals can bear in social space.