Background: Individuals with Williams syndrome (WS) show a disharmonic linguistic profile with a clear pattern of strengths and weaknesses. Despite their sociable nature, atypical socio-communicative abilities and deficits in communication and relationship with others have been found. Aim: The aim of the present study was to investigate whether linguistic skills (LS) were in line with the pragmatic and social use of language and the cognitive development of 32 individuals with WS (18 boys and 14 girls) with a mean chronological age of 12.3 (±4.4) years. To examine the relationship between language and mental age (MA) at different ages, the issue was investigated in children and adolescents/young adults with WS. Method: Measures of LS, including lexical and morphosyntactic competences, and adaptive socio-communicative abilities (ASCA), pertaining to the use of language in daily living social context, were compared with the MA of participants. In a second step, participants with WS were split into two subgroups based on age, and the relationship between LS, ASCA and MA was studied. Results: Although expressive and receptive LS were generally found to be in line with or better than would be expected for MA, specific deficits in receptive ASCA were documented. LS and ASCA appeared to have a different evolution during the different time windows considered. Conclusions: Our results underlined the importance of assessing linguistic abilities in the context of adaptive functioning, to guide educational and rehabilitative strategies for individuals with WS.