While traditional views of literacy assume that discourse is either written or oral, an alternative perspective considers different discourse samples as part of the linguistic repertoire of the speech community. Placing this perspective in a sociolinguistic context and taking language use rather than form as the starting point for analysis, it is seen that the media of literacy available to the language user are options from which the speaker chooses. Like other linguistic choices they are dependent on the communication situation. Data collected in a larger study on computer communication, which were analyzed to identify co-occurrences of media and modes with context aspects, illustrate, in an office context, a proposed taxonomy of the use of four communication media (face-to-face, telephone, paper, and computer) and related modes. The face-to-face medium includes modes such as meetings, lunchtime conversation, and office conversation. The computer-mediated communication medium includes computer messages, computer mail, and document modes. The taxonomy defines the rules used in switching media and modes and accounts for both code-switching situations and single-code choices. It treats medium- and mode-switching as a variation of code-switching. (MSE)