At about 7 months of age, infants listen longer to sentences containing familiar words--but not deviant pronunciations of familiar words (Jusczyk & Aslin, 1995). This finding suggests that infants are able to segment familiar words from fluent speech and that they store words in sufficient phonological detail to recognize deviations from a familiar word. This finding does not examine whether it is, nevertheless, easier for infants to segment words from sentences when these words sound similar to familiar words. Across three experiments, the present study investigates whether familiarity with a word helps infants segment similar-sounding words from fluent speech and if they are able to discriminate these similar-sounding words from other words later on. Results suggest that word-form familiarity may be a powerful tool bootstrapping further lexical acquisition.