Though it is commonly assumed that collective nouns are specific to the domain of individuals, e.g., committee of women, in fact the category is much more general and covers also abstract objects such as eventualities, e.g., series of murders, and numbers, e.g., sequence of integers. Furthermore, recent findings suggest that collective nouns do not constitute a uniform category. Rather, there are SPATIAL collectives referring to topological configurations, e.g., pile of dishes, and SOCIAL collectives designating organizations based on membership, e.g., committee of women (Pearson 2011, de Vries 2015, Henderson 2017, Zwarts 2020). 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 in (1)‒(2) 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. (1) SPATIAL: kwiat 'flower' ~ kwiat-y 'flowers' ⇒ kwieci-e `clump of flowers' (2) SOCIAL: duchowny 'priest' ~ duchown-i 'priests' ⇒ duchowień-stwo 'collective of priests, clergy'