This study investigated the use of various forms of computer-mediated communication (CMC) to support the formation of a knowledge-building community (KBC) in teacher education. A KBC involves students working in small and large groups to solve "real world" problems, and in the process develop skills of negotiation, communication, and collaboration. Emphasis is placed on authentic problems that are linked to a school context. The findings showed that students preferred to use forums available to all participants. Also, they used the forums in ways that were not anticipated by the authors. Many students made use of other modes of CMC such as e-mail and synchronous forums downloaded from the Web. Many of the skills used in mediating face-to-face discussion could be transferred to the online situation. (Contains 21 references.) (Author)