Children with Williams syndrome (WS) have been reported to often face problems in daily communication and to have deficits in their pragmatic language abilities. To test this hypothesis, we examined whether children with WS could modify their verbal communication according to others' attention in order to share what they did. The children with WS and typically developing (TD) children were asked to accomplish tasks as quickly as possible while the experimenter was attending to or not attending to them during and after their accomplishment. The results showed that although TD children verbalized more when they were not attended to than attended to, children with WS verbalized more when they were attended to than not attended to. The results indicate that children with WS may have deficits in attention-sharing communication, suggesting a part of their pragmatic abilities is impaired. (Contains 1 figure.)