It is proposed that genre/discourse community interaction is a critical element in the teaching of English for Special Purposes (ESP). All text is intended to promote interaction between writer and audience. Authentic texts generally have a central purpose: to change opinion, introduce a new idea, or encourage a specific action. The principle features of a written text that qualifies it as a genre include: (1) a name by which members of the discourse community can readily identify it, such as "grant" or "memo"; (2) a characteristic form and style that distinguish it from other genres; (3) a specific form and style that serve communicative or community purposes; and (4) conventions of form, style, and purpose within a range of permitted variation. Students of ESP must be introduced to each of these features. Suggestions for classroom instruction are to: begin with familiar genres; use authentic texts that are also prototypes accepted within the targeted discourse community; use expert readers and writers as resources concerning text purpose, form, and style; contextualize texts; and emphasize features necessary to community purposes. (MSE)