The paper discusses the role of context in a collaborative design process, with a Web-based environment for distributed architecture - engineering - construction teamwork. During this process, the decision is made collectively and progressively after a phase of negotiation among specialists from different domains. The goal of the project is to improve the teamwork performance by allowing participants (the specialists in different domains) to constitute a team and to collaborate in the project by interacting remotely in a virtual environment. The environment takes advantage of the current information technology to permit specialists to maintain their personal contexts and a shared team context, in which knowledge is acquired in concrete situations (i.e. knowledge is acquired in its context of use). The paper presents how context intervenes: (1) in the acquisition of the different types of knowledge as an intrinsic part of any negotiation, (2) how a decision making results of a progressive and negotiated building of a shared proceduralized context among the team participants, and (3) how participants in the teamwork can structure their own contextual knowledge (the individual contexts) and share, at least partially, their individual's tacit knowledge with other participants (in the team context). As a consequence, it emerges that design and learning are similar tasks, i.e. design is "learning by negotiating".