This study investigated the phonetic processing of new words in 3-to-8-year-old children with Williams syndrome (WS). Word-learning abilities were evaluated with a task involving the learning of two phonetically similar words for two different objects. Overall, children with WS were able to process fine phonetic details while establishing new word-object links. Their performance pattern was predicted by their mental age and was characterized by an asymmetrical processing of consonant and vowel information to the advantage of consonants found with this task in younger, typically developing, children. These results show delayed but relatively preserved word-learning abilities in WS, and this trajectory is discussed in comparison with typical development.