We presented 19-month-old infants with a novel phonotactic learning task. It required learning four phonotactic patterns over 3.5 min of exposure. During testing, successful discrimination of the test items required detecting the difference between the trained consonant clusters and unfamiliar clusters that incorporated identical consonants in novel pairings. The findings indicate that phonotactic knowledge is tied to the lexicon early in vocabulary development. Importantly, only infants with the smallest vocabularies exhibited learning of the phonotactic patterns;