The status of children’s acquisition of grammatical categories and in particular of auxiliaries continues to be debated. On the one hand, a number of corpus studies suggest that auxiliaries and similar categories are absent early on (e.g., Wijnen 1996/1997, Schlyter 2003). On the other hand, experimental studies indicate that syntactic competence for functional categories is available to toddlers and even infants (e.g., Gerken & McIntosh 1993, Santelmann & Jusczyk 1998). This study investigates the acquisition of auxiliaries in child French and evaluates these two perspectives using a new corpus of over 5000 child utterances containing cross-sectional speech samples from 18 children, ages 1;11 – 2;11. Subjects were presented with a standardized set of props and questions designed to trigger utterances with verbs and auxiliaries. Data collection and analysis involved an innovative digital recording set-up, digital transcription technology and editing software, and more detailed data analysis, including spectrograms. The results reveal that auxiliaries and modals are evidenced in all children from the earliest ages. Children produce a variety of auxiliary/modal forms: full auxiliaries, phonetically and phonologically reduced auxiliaries, “filler” vowels standing for auxiliaries, as well as subject agreement markers that precede nonfinite verbs and that implicate the presence of a finite auxiliary/modal. These findings strengthen previous experimental results regarding children’s knowledge of functional categories by providing corroboration from a corpus study.