The Open University has experimented with a number of small-scale uses of computer conferencing with 25 to 50 students. Many of these trials have involved the use of the conferencing system FirstClass. The results of these have shown how exciting and educationally valuable this medium can be (Mason, 1994b). However, it is the conclusion of those involved in many of these trials that no ideal model has yet been identified for applying these successes to large courses of 1,000 to 5,000 students. Some of the suggestion's under consideration include: the extension and enhancement of peer learning groups; the use of "master classes," in which a few students interact with an expert while the remainder can read only; increased input from central academic staff who normally write courses rather than interact with students; the use of World Wide Web facilities integrated with conferencing facilities; and the development of a few specialist conferencing tutors rather than the expectation that all tutors will be trained and paid for conferencing duties. A variety of uses of conferencing are jumbled together among these suggestions, and it is important to distinguish them: conferencing used for teaching (the content of the course) and conferencing used for tutoring (supporting the student); conferencing used for course delivery (of articles, updating material, directives from the course team) and conferencing used for interaction (between students and teachers). While it is possible, perhaps even desirable, that the OU use conferencing for all these things, it is necessary to be clear on the objectives for each type of use. Over the next few years as the OU expands into continental Europe, extensive use will be made of computer conferencing, and many of these uses will be integrated with various forms of multimedia educational facilities, such as CD-ROM. During this period, the OU will be experimenting widely with a variety of large-scale conferencing models.