Language samples elicited through a picture description task were recorded from 38 adolescents and adults with Williams syndrome (WS) and one control group matched on age, and another matched on age, IQ, and vocabulary knowledge. The samples were coded for use of various types of inferences, dramatic devices, and verbal fillers; acoustic analyses of prosodic features were carried out, and an independent group of judges provided global ratings of the overall expressiveness of the language. In addition, a standardized measure of social adaptive functioning was administered to the parents of the participants with WS. The findings revealed distinctive developmental trends in the use of expressive content and prosodic patterns by adolescents and adults with WS that were not evident among the controls. Ratings of expressiveness by naive judges of the speech samples produced by the participants with WS were related to parent evaluations of adaptive social communication skills; however, the verbal productions of this group were not judged to be significantly more expressive than those of controls.