This article describes and outlines the implications of a one-year case study of students' use of the computer conferencing facility of a postgraduate module for special educational needs coordinators (SENCOs) at a distance-learning institution. This facility incorporates a virtual space for a guest expert. The aim of the study was to inform future development of courses at a time when computer conferencing was just becoming widespread in the university concerned. Quantitative data associated with the volume and patterns of individual participation in the computer conference were collected as well as interview material from students, tutors and the guest expert. Findings from the study indicate that computer conferencing has the potential to facilitate the professional development of teachers as reflective practitioners and researchers. However, they also point to a number of barriers to student participation that must be addressed. These include access issues related to time constraints, unfamiliarity with the medium, and lack of confidence in expressing personal views in a public arena. A major conclusion drawn from this study is that it may be appropriate to consider future developments which incorporate the assumption that, in computer conferences of large professional development courses, students are much more likely to participate through reading rather than making personal contributions to conference discussions. This opens the possibility of reconceptualising the role of the guest expert as two or more discussants with relevant expertise dialoguing with each other while students follow a threaded discussion and/or make personal contributions.