Two experiments investigated how both shared and privileged knowledge affect reference production during dialogue. Dyads of participants jointly established routes for an imaginary person. Each participant was given a map featuring shared landmarks (i.e., they also appeared on the partner's map) and privileged landmarks (i.e., they did not appear on the partner's map). Analyses focused on which references participants included in their utterances. Results showed that the production of references that had previously been explicitly accepted and hence added to the speakers' common ground was affected by information availability. Furthermore, the participants compensated for the influence of information availability by keeping track of the information their partners were likely to lack and producing it when necessary. Results are discussed with regard to collaboration and the influence of privileged knowledge during dialogue. (Contains 4 tables and 4 figures.)