How does mass–count syntax affect word meaning? Many theorists haveproposed that count nouns denote individuals, whereas mass nouns do not(Bloom, 1999; Gordon, 1985; Link, 1983), a proposal that is supported byprototypical examples of each (table, water). However, studies of quantityjudgments in 4-year-olds and adults demonstrate that some mass nouns(furniture) do denote individuals (Barner & Snedeker, 2005). This isproblematic for bootstrapping theories that posit one-to-onesyntax-semantics mappings (individual ↔ count; nonindividual ↔ mass; Bloom,1999), unless mass nouns that denote individuals are late-learnedexceptions to mappings. This article investigates this possibility in3-year-olds and adults using 2 methods: word extension and quantityjudgment. Both methods indicate that novel mass nouns can denoteindividuals in both age groups, and thus fail to support simplifiedsyntax-semantics mappings. Also, differences between word extension andquantity judgment raise the possibility that the tasks measure differentunderlying knowledge.