Predicates like gather and be numerous have both been described as 'collective predicates,' since they predicate something of a plurality. The two classes of predicates differ, however, with respect to plural quantifiers (e.g. all), which are grammatical with gather-type predicates but ungrammatical with numerous-type predicates. Here, I show that the gather/numerous opposition derives from mereological properties that are familiar from the domains of telicity and mass/count. I address problems of undergeneration and overgeneration with two technical innovations: first, I weaken the property of divisibility to Champollion's (2015) property of stratified reference; second, I provide mechanisms to rule out accidental satisfaction of the logical property. From a broader perspective, we place collective predication in a larger context by building empirical connections to mass/count and collectivity across semantic domains.