This paper explores the item-based nature of child language acquisition by examining data from the CHILDES database (MacWhinney 2000). Two studies are explicated: the first uses pooled data from several children, and the second follows a single child longitudinally. The results show that the learning of the complex construction consisting of a main clause followed by an infinitival compliment, e.g. I want to play, center around a single verb, want, even though other candidate verbs exist in the children’s vocabulary. We provide empirical evidence to show that children initially learn grammar via item-based units and gradually break down complex constructions as units into smaller pieces in a process that leads towards the organization of language into the abstract categories consistent with a fully competent adult grammar.