In this paper I give a brief outline of Chouliaraki and Fairclough’s theory of the role of language within and between social practice and Bernstein’s theory of recontextualisation, and then go on to situate literacy within the moment of discourse and explain how literacy will vary according to social practice. I illustrate how critical discourse analysis can illuminate this variation by analysing three events involving letter writing; two of which take place in educational practices. This analysis shows how letter writing can be transformed into an imaginary act in the classroom.