Two experiments tested whether phonological phrase boundaries constrain online syntactic analysis in French. Pairs of homophones belonging to different syntactic categories (verb and adjective) were used to create sentences with a local syntactic ambiguity (e.g., [le petit chien "mort"], in English, the "dead" little dog, vs. [le petit chien] ["mord"], in English, the little dog "bites", where brackets indicate phonological phrase boundaries). An expert speaker recorded the sentences with either a maximally informative prosody or a minimally informative one. Participants correctly assigned the appropriate syntactic category to the target word, even without any access to the lexical disambiguating information, in both a completion task (Experiment 1) and an abstract word detection task (Experiment 2). The size of the experimental effect was modulated by the prosodic manipulation (maximally vs. minimally informative), guaranteeing that prosody played a crucial role in disambiguation. The authors discuss the implications of these results for models of online speech perception and language acquisition. (Contains 4 figures and 9 footnotes.)