How do children start connecting language to things in the world? Some of the first words infants understand are nouns, and it is argued that the entities that nouns describe are either (1) object representations created by perceptual processes that are indexed in space, (2) 'sortal' representations that are indexed based on their kind membership, or (3) 'mental files' indexed in relation to knowledge states of communicative partners. I will argue that there are issues with all of these options. The issue with (1) is that it does not empirically account for even infant behavior, (2) might be a category error, and (3) fails as a theory of adult state. Instead, I will propose that for infants, children, (and adults) nouns describe 'discourse referents': entities that are indexed by grammar in relation to the common ground. I first explore the role of discourse referents for adults, with experimental work on the ‘formal link’ condition for pronoun resolution. Then I will present developmental work on two case studies -- 'mutual exclusivity' and 'false descriptions' -- that probe the relationship of descriptive content and grammar in how children represent entities.