Infants who are in the process of acquiring their mother tongue have to find a way of segmenting the continuous speech stream into word-sized units. We present an experiment showing that French 16-month-olds are able to exploit phonological phrase boundaries in order to constrain lexical access. Using the conditioned head-turning technique, we showed that infants trained to turn their head for a bisyllabic word responded more often to sentences that contained this word, than to sentences that contained both syllables of this word separated by a phonological phrase boundary. We compare these results with similar results obtained with English-speaking infants, and discuss their implication for lexical and syntactic acquisition.