This paper examines the elements, structure and formation process of derived categories, by analyzing the properties of nouns derived from adjectives in Spanish. It is shown that, although it is commonly assumed that deadjectival nouns denote qualities (wisdom, beauty) or states (sadness, perplexity), there is a group (imprudence, cruelty) that refers to occurrences of events (Beauseroy, 2009). It is proposed that such occurrential nominalizations are possible only when derived from evaluative adjectives because only these can be predicated of events in addition to the sentient individual (Stowell, 1991).