Williams syndrome, a genetic disorder caused by a microdeletion of approximately 25 genes on chromosome 7q11.23, is associated with mild to moderate intellectual disability or learning difficulties. Most individuals with Williams syndrome evidence a cognitive profile including relative strengths in verbal short-term memory and language, and considerable weakness in visuospatial construction. The syndrome has often been argued to provide strong evidence for the independence of language from other aspects of cognition. We provide a brief history of early research on the language abilities of individuals with Williams syndrome and then review contemporary studies of language and cognition in Williams syndrome, beginning with a consideration of performance on standardized assessments. In the remainder of the article, we first consider early language acquisition, with a focus on speech production and perception, vocabulary acquisition, and communicative/pragmatic development and then consider the language abilities of school-age children and adolescents, focusing on semantics, grammar, and pragmatics. We argue that rather than being the paradigm case for the independence of language from cognition, Williams syndrome provides strong evidence of the interdependence of many aspects of language and cognition. (Contains 3 figures.)