The concerns of this chapter are with the relations between well-formed discourse, describable in the terms set out in the preceding pages, and the processes of learning and teaching; between the purposes for which society sets up and maintains schools and classrooms, and the text that is created in the course of what goes on in them. My first concern will be with what is observable of the ways in which young newcomers learn what the rules are. This will involve the examination of passages of recorded and transcribed text, and a selective use of the coding system derived from the Birmingham model already described and illustrated. Second, there is a complementary question to be asked, and more briefly answered: how do teachers learn to operate the rules that obtain in their part in the discourse, and to exercise their varied, demanding rights and responsibilities in it? Third, there is a question to be asked about the discourse itself. Does its orderly and rule-governed character derive from the necessities of learning and teaching and does it serve those purposes uniquely well? Or are there other sorts of didactic discourse, still awaiting systematic and linguistically principled description?