Background: Children with Down's syndrome seem to show a preference for the use of gestural rather than vocal productions during the first stages of language development. This "gestural advantage" could actually be due to a developmental strategy used to compensate the difficulties in verbal production that are typical of language development in this population. Aims: The principal aim of the present study is to analyse the relationships between gesture production and vocabulary development in children with Down's syndrome, verifying the existence of any similarities with the processes that characterize typical development. Methods & Procedures: Twenty 36-month-old Italian children with Down's syndrome participated in the study. Each child's spontaneous gestural and vocal production was assessed during a mother-and-child play session. Their psychomotor development was evaluated using the Brunet-Lezine Scale of Infant Development; and their vocabulary size, with regards both production and comprehension, was assessed using the Italian version of the MacArthur Communicative Development Inventory (CDI). Following a longitudinal perspective, parents were requested to complete the inventory at 6 months after the first evaluation (i.e., at 42 months). Data analyses focused both on the concurrent relations of gesture production, vocabulary size and psychomotor development, and on the longitudinal relations between gesture production and subsequent vocabulary development. Outcomes & Results: As regards concurrent relationships, gesture production appeared to be related both to psychomotor development and to word comprehension, but not to word production. Nevertheless, as regards longitudinal relationships, gesture production at 36 months was significantly correlated to the subsequent vocabulary production, assessed at 42 months using the MacArthur Communicative Development Inventory (CDI), though this relationship appeared to be mediated by word comprehension. Conclusions & Implications: Two processes in the gesture production of children with Down's syndrome appear to be similar to those previously identified in typically developing children: (1) the role of gestures as a "bridge" between word comprehension and word production; and (2) the predictive role of gestures, in association with comprehension, on vocabulary development. (Contains 4 tables.)