This contribution argues for an investigation of expert/non-expert discourse in an interactive frame of references which accommodates the constitutive systems of text, interpersonal orientation and interaction. Depending on the interlocutors' communicative goals, references to these systems are represented explicitly or implicitly.

Part I presents a frame analysis of expert/non-expert discourse from both linguistic and social-context viewpoints. Here, special reference is given to the question of how the communication act plus/minus-validity claim accommodates expert/non-expert discourse. Part II presents a micro investigation of expert/non-expert discourse. It compares and contrasts written and spoken expert/non-expert discourse in the domain of institutional communication. The data stem from the field of computer-application discourse and are analysed with regard to the degree of explicitness of textual, interactional and interpersonal references. The results obtained are refined by the explicit accommodation of the variables intimacy and power. In conclusion, face-to-face expert/non-expert discourse is not only characterized by a high degree of explicitness of the textual system, i.e. the linguistic representation of expert knowledge, but also by a high degree of explicitness of the interpersonal and interactional systems.