Over three years this study investigated the use of an asynchronous web-based conference to facilitate the reflective thinking of 35 intern teachers using a conceptual framework from the literature on teacher reflection, computer-mediated communication, and social cognition. Content analysis of the interns' online messages revealed significant between- groups differences, indicating that constructs identified in the framework could influence the development of reflective thinking online. Four themes emerged that appeared to shape the kinds of issues and the depth of thinking revealed: (a) clearly articulating purposes for discussions, (b) framing the kind of participation expected, (c) including both experienced and beginning teachers, and (d) establishing trust among participants that encouraged ownership. This study suggests that web-based conferences are sensitive to relatively light instructional and social pressures.