Previous studies of linguistic and memory abilities in Italian-speaking children with Williams syndrome (WS) and Down syndrome (DS) are briefly reviewed. New data on linguistic performance of 6 Italian children with WS between 3 and 6 years of age are presented and compared with data on linguistic performance of 6 children with DS selected from a larger sample and matched for chronological age and vocabulary size and of 6 typically developing (TD) younger children matched for mental age and vocabulary size. The language measures also included a parent report of early phrase structure, a naming test, and a sentence repetition task. Analyses revealed that the 3 groups of children were at the same productive vocabulary level, but showed different patterns in sentence production and repetition. Children with WS produced more complete sentences, similar to TD children at the same vocabulary size, whereas children with DS produced more telegraphic and incomplete sentences. The difference between children with DS and those with WS was more marked on the repetition task, suggesting that phonological short-term memory may play a greater role when sentence production is measured through repetition. In addition, qualitative analysis of errors produced in the repetition test revealed interesting differences among the 3 groups. These results from younger children confirm and extend previous findings with older children and adolescents with WS. They further suggest that the apparently spared linguistic abilities of children with WS could emerge as an artifact of comparisons made to 34children with DS, whose sentence production competence is more compromised relative to other verbal and nonverbal abilities.