Our analyses suggest that early fillers are premorphological. They help children realize phonoprosodic features, and reflect the distributional regularities of child-directed speech, but are not used to differentiate nouns from verbs, a differentiation that starts to show up a few months after their appearance. The analysis of verbal inflectional morphology confirms these results, showing that, at first, verbs are not treated differently from nouns. The results of a comprehension task administered longitudinally to one of the children are also reported. In this task the child has to attribute an action or object meaning to homophonous or nonce words on the sole basis of the grammatical context in which they occur. The more mature understanding of the distinction between noun and verb frames required by the comprehension task sheds further light on the early psychological reality of Nouns and Verbs for young children.