Human social interaction depends on individuals identifying the common ground they have with others, based both on personally shared experiences and on cultural common ground that all members of the group share. We introduced 3- and 5-year-old children to a culturally well-known object and a novel object. An experimenter then entered and asked, "What is that?", either as a request for information or in a recognitory way. When she was requesting information, both 3- and 5-year-olds assumed she was asking about the novel object. When she seemed to recognize an object, 5-year-olds assumed she was referring to the culturally well-known object. Thus, by 3 years of age, children are beginning to understand that they share cultural common ground with other members of their group. (Contains 3 figures and 3 footnotes.)