This study examines the role of functional morphemes in the earliest stage of lexical development. Recent research showed that prelinguistic infants can perceive functional morphemes. We inquire whether infants use frequent functors to segment potential word forms. French-learning 8-month-olds were familiarized to two utterance types: a novel noun following a functor, and another novel noun following a prosodically matched nonsense functor. After familiarization, infants' segmentation of the two nouns was assessed in a test phase presenting the nouns in isolation. Infants in Experiment 1 showed evidence of using both frequent functors "des" and "mes" (as opposed to the nonsense functor "kes") to segment the nouns, suggesting also that they had specific representations of the functors. The infrequent functor "vos" in Experiment 2 did not facilitate segmentation. Frequency is thus a crucial factor. Our findings demonstrate that frequent functors can bootstrap infants into early lexical learning. Furthermore, the effect of functors for initial word segmentation is likely universal.