Early acquisition of nouns and verbs across languages is a key issue for a number of recent studies that question the reality of the ‘noun-bias’ and wonder about the reasons why it exists as they explore the role of cognitive vs. more language-specific input factors. Addressing this issue, the present study investigates how the noun and verb word classes develop in the free speech of a French child between the ages of 1;2 and 2;6, from the perspective of semantic and grammatical development. The analyses indicate that, in French acquisition, nouns clearly predominate over verbs until age 1;8 at least, but that verbs are produced in the early stages. Concrete object names among nouns and concrete action verbs among verbs were found to be the most prevalent categories, but they were not the earliest to appear and their distribution revealed an asymmetry in the conceptual packaging of nouns and verbs. Verb grammaticalization, assessed through inflection and auxiliary use, lagged somewhat behind noun grammaticalization, assessed through determiner use. This result supports the hypothesized noun–verb grammatical asynchrony. Verb grammaticalization seems to be related to the production of concrete action verbs, and noun grammaticalization to that of concrete object nouns, indicating interactions between semantic and grammatical development. These findings, discussed in a cross-linguistic perspective, suggest that both conceptual and grammatical packaging are important and interacting factors in noun and verb development, and argue in favour of a constructivist approach to language acquisition.