Communication between experts and laypeople has become an almost ubiquitous phenomenon. However, this dimension has been neglected in psychological research on expertise where the expert usually is modeled as an isolated problem solver. The present paper argues that in particular the expert’s specialized knowledge often proves to be an obstacle to effective interpersonal communication with laypersons. The theoretical discussion of the notion of community membership shows that it is a necessary but complex demand for experts to take a layperson’s perspective in order to establish common ground. In an empirical study with two types of computer experts it was investigated in how far experts are able to anticipate what laypersons know about their domain. A second study analyzed how different aspects of knowledge are differently considered by expert architects when adapting to a lay audience.