DDPTC07This paper analyzes a professional development Web site for teachers that features 'virtual classroom visits' - video clips of teachers teaching, together with asynchronous forums for discussing the videos. The site was designed with the explicit goal of fostering community among teachers and teachers in training, where community is defined in part as self-sustaining, ongoing interaction. We analyze the relationship between the design of the ?classroom visit' interface and the textual conversations taking place there, pointing out ways in which unintentional bias in the representation of gender in the videos is reflected in asymmetries in participation by males and females, to the detriment of the community design goal. Based on this evidence, we argue that designers of CMC systems should take user gender into account in creating multimodal interfaces that represent humans directly.