One highly influential finding that suggests that syllabic units are instrumental in speech perception is the crossover interaction between target type and word type observed in the sequence detection task. In this paper we review our recent studies with French speakers using the same task. Overall the findings fail to replicate the "syllable effect" and indicate that the observed effects are primarily due to the time course of the arrival of phonetic information in the carrier stimuli. These data argue against an early syllabic classification mechanism in speech perception, but other results that we have obtained suggest an important role of syllable structure and more specifically onsets in speech segmentation.