This paper addresses a fundamental problem of derivational morphology: which meanings are possible for the words of a given morphological category, which forms can be chosen to express a given meaning, and what is the role of the base in these mappings of form and meaning? In a broad empirical study we examine the extent to which two types of nominalizations in English – conversion nouns and -ing nominalizations – can express either eventive or referential readings, can be quantified as either count or mass, and can be based on verbs of particular aspectual classes (state, activity, accomplishment, achievement, semelfactive). Past literature (for example, Grimshaw 1990 Brinton 1995, 1998 Borer 2013) has suggested an association between conversion nominalization, count quantification, and referential reading on the one hand, and between -ing nominalization, mass quantification and eventive reading on the other. Using a subset of the data reported in Andreou & Lieber (2020), we give statistical evidence that the relationship between morphological form, type of quantification, and aspectual class of base verb is neither categorical, as the literature suggests, nor completely free, but rather is probabilistic. We provide both a univariate analysis and a multivariate analysis (using conditional inference trees) that show that the relationship among the variables of morphological form, eventivity, quantification and aspectual class of base is complex. Tendencies sometimes go in the direction suggested by past literature (e.g. -ing forms tend to be eventive), but sometimes contradict past predictions (conversion also tends to be eventive). We also document that an important role is played by the specific verb underlying the nominalization rather than the aspectual class of verb. Finally, we consider what the pattern of polysemy that we uncover suggests with respect to theoretical modeling, looking at syntactic models (Distributed Morphology), lexical semantic models (the Lexical Semantic Framework), Analogical Models, and Distributional Semantics.