Referential success depends on choice of referring expression.The choice of referring expression will depend on contextualfactors as well as factors related to speaker and addresseeknowledge. A shared-learning paradigm was used in whichpartners learned names of objects together and separately beforea referential task. Items differed on commonality, with someindependently rated as more common and some as more rare.Speakers were less likely to use names versus other forms whenitems were rare than common (p<0.001) and less likely to usenames when items were new than learned together (p<0.001).Asymmetry effects showed that speakers were more likely touse a name when the addressee was deemed moreknowledgeable in post-test ratings (p<0.01). Together, we takethis to show speakers choose to use a name versus a descriptionbased on the likelihood that their interlocutor will know thename. Factors affecting the likelihood include prior knowledgeof what a typical addressee will know and shared experience,which includes inferring an interlocutor’s expertise, asdynamically updated during a dialog.