This paper describes de results of a study evaluating the effects of computer mediation on collaboratively solving architectural design problems.Pairs of graduate design students were asked to work on a landscape architecture design problem via computer terminals.In one condition they were allowed to communicate with an electronic whiteboard and a chat-line while in the other, the chat-line was substituted with videoconferencing (real-time video and audio).The protocols were evaluated according to two models.First, they were coded according to the pattern of collaboration, distinguishing meta-planning, negotiation; evaluation, and individual work No differences were found between the two groups when coded this way.The protocols were also coded in terms of the problem-solving content, distinguishing task-related exchanges, interface related exchanges, low-level design exchanges, and highlevel design exchanges.The results showed that in the bandwidth-limited chat-line condition, participants cut down task and interface-related as well as low-level design exchanges but attempted to maintain the same amount of high-level design exchanges.When de final designs wene evaluated by professional architects, no differences were found between two conditions indicating that chat-line participants implicitly compensate for the narrower bandwidth interface.