In 2 studies, we investigated how peers establish a "referential pact" to call something, for example, a "cushion" versus a "pillow" (both equally felicitous). In Study 1, pairs of 4-and 6-year-old German-speaking peers established a referential pact for an artifact, for example, a "woman's shoe," in a referential communication task. Six-year-olds, but not 4-year-olds, continued to use these same expressions with the same partner (even when they were overinformative) but shifted to simpler expressions, for example, "shoe," with a new partner. In Study 2, both age groups were successful in establishing such partner-specific referential pacts with a peer when using a proper name. These results suggest that even preschool children appreciate something of the conventional nature of linguistic expressions, with significant flexibility emerging between ages 4 and 6.