Since a discourse community may have its membership assigned both on the basis of speech or of writing, it follows that the concept of discourse community needs to be both medium-neutral and unconstrained by space and time. The defining characteristics of a discourse community might be (1) communality of interest, (2) mechanisms for intercommunication between members, (3) survival by providing information and feedback, (4) development of genre-specific discoursal expectations, (5) possession of an embedded dynamic towards an increasingly shared and specialized terminology, and (6) a critical mass of members with a suitable degree of relevant discoursal and content expertise. Characterizing discourse communities in this way leads to several consequences--the most salient being that the fact that groups have things in common in no way implies that such groups form discourse communities. In addition, sketching the boundaries of discourse communities implies that individuals may belong to several communities and will vary in the number of communities they belong to and thus in the number of genres they command. Other points are that the criteria presented do not impose preconditions as to a prior expectation of a high level of personal involvement among members; a community may or may not be connected to what members perceive as the central activities and concerns of their lives; and discourse communities will vary in the extent to which they are norm developed or set in their ways. (References are attached.) (NKA)