In this article we present data from two sets of experiments designed to investigate how children and adult speakers of English and Kannada (Dravidian) interpret scopally ambiguous sentences containing numerally quantified noun phrases and negation (e.g. Donald didn't find two guys). We use this kind of sentence as a way to find evidence in children's linguistic representations for the hierarchical structure and the abstract relations defined over these structures (in particular, the relation of c-command) that linguists take to be at the core of grammatical knowledge. Specifically, we uncover the existence of systematic differences in the way that children and adult speakers resolve these ambiguities, independent of the language they speak. That is, while adults can easily access either scope interpretation, 4-year-old children display a strong preference for the scopal interpretation of the quantified elements which corresponds to their surface syntactic position. Crucially, however, we show that children's interpretations are constrained by the surface hierarchical relations (i.e. the c-command relations) between these elements and not by their linear order. Children's non-adult interpretations are therefore informative about the nature of the syntactic representations they entertain and the rules they use to determine the meaning of a sentence from its structure.