This study investigates the syllable's role in the normal reading acquisition of French children at three grade levels (1st, 3rd, and 5th), using a modified version of Cole, Magnan, and Grainger's (1999) paradigm. We focused on the effects of syllable frequency and word frequency. The results suggest that from the first to third years of reading instruction, children process high-frequency syllables as syllable units while processing low-frequency syllables as phoneme units. In fifth graders, syllable-based processing is extended to both high and low syllable frequencies, primarily due to CVC structures with high-frequency syllables. Lexical frequency does not significantly influence syllable processing. These findings reveal that the syllable is an early prelexical unit modulated initially by syllable frequency, and subsequently by grapheme-to-phoneme correspondences. High-frequency syllables did not produce inhibitory effects. Consequently, results are compatible with Levelt and Wheeldon's (1994) mental syllabary hypothesis. Implications for specific reading training and syllable based remediation are discussed. (Contains 4 figures and 3 tables.)