Learning to argue is a key academic purpose for both first and second language students. It has been claimed that computer mediated asynchronous text-based conferencing is a useful medium for developing argumentation skills (Andriessen, Baker, & Suthers, 2003). This paper reports on two research studies which explore this claim. One study focused on secondary school history students' use of conferencing to debate interpretations of historical events, the other investigated undergraduate students (in Health and Social Care) exchanging views on controversies surrounding complementary and alternative medicine. In general, research into electronic conferencing and argumentation has tended to be located within cognitive or sociocultural paradigms. In contrast, the studies reported on here used the framework and tools of systemic functional linguistics (supported by concordancing software). Interpretation of the linguistic findings was also aided by questionnaire and interview data. The analyses revealed some significant trends across both student cohorts. Overall, students were more inclined to make or support claims rather than counter or challenge them. Other significant trends included the fact that some sub-topics resulted in sustained argumentative dialogue whilst others quickly petered out. Analysis indicates that the linguistic expression of claims may partly explain this phenomenon. The authors argue that functional linguistic analysis (from text to clause level) provides a useful basis for considering the pedagogic potential of conferencing in facilitating argumentative dialogue and student learning. (Contains 4 figures and 5 tables.)