To characterize autism spectrum-related symptomatology in children with Williams syndrome (WS) with phrase speech or fluent language, the Autism Diagnostic Observation Schedule Module 2 or 3 was administered. The cutoff for autism spectrum was met by 35% (14/40) who completed Module 2 and 30% (18/60) who completed Module 3. Similarities and differences in socio-communicative strengths and weaknesses as a function of language ability were identified. Symptom severity was negatively associated with IQ for participants with phrase speech but not for those with fluent language. The findings suggest an elevated risk of ASD for individuals with WS relative to the general population and contribute to a more nuanced sense of the socio-communicative functioning of children with WS.