Large-scale engineering projects are created by teams of cooperating engineers who must share knowledge about the project as it evolves. Sharing of engineering knowledge is actually made more difficult by modern engineering environments First, the computerized engineering environment requires that much of the knowledge sharing be on a tool-to-tool basis, rather than human-to-human Computer tools (3-D modellers, analysis and stimulation tools, etc ) have become the locus of much of the engineering information for a project These tools embody engineering assumptions and methods that are not understood in detail by their user engineers Moreover, the tools use specialised internal representations that are not understood by other tools Second, the connectivity enabled by the modern networked engineering environment greatly increases the complexity of the interaction environment It is virtually impossible for engineers to know who is likely to be impacted by their decisions, and what issues they need to negotiate. The Cosmos project is part of a collection of research efforts that is creating technology to allow engineers to share knowledge about a design through their tools when engineers modify a design, the tools they are using automatically provide relevant updates to other engineers whose work is affected by the change Cosmos's role is to support engineering negotiation, illustrated here in the domain of active control of spaceborne structures The paper descnbes the Cosmos Phase I implementation, which provides negotiation support for engineers from different disciplines cooperating on a design, lessons learned from Phase I, and our current activities in building the Phase II implementation