In two experiments, the use of mutual exclusivity in the naming of whole objects was examined in monolingual and bilingual 3- and 6-year-olds. Once an object has a known name, then via principles of mutual exclusivity it is often assumed that a new name given to the object must refer to some part, substance, or other property of the object. However, because bilingual children must suspend mutual exclusivity assumptions between languages, they may be more willing to accept two names for an object within a language. In the current research, the use of mutual exclusivity in the naming of whole objects was found across monolingual and bilingual children, although older bilingual children were significantly less inclined to use mutual exclusivity than were older monolingual children. These results are discussed in terms of differences in monolingual and bilingual children's word learning.