Interorganizational projects can provide a vehicle for innovation, despite the professional and organizational barriers that confront this form of organizing. The case of fire engineering shows how such projects use simulation technology as a boundary object to foster innovation in a new organizational field. Engineers use simulation technology to produce radical changes in fire control and management, such as using elevators to evacuate buildings during emergencies. A framework is developed that explores how decisions can be reached and tensions resolved amongst multiple, diverse, and discordant actors striving for a shared appreciation of negotiated futures. This framework extends theories of engineering knowledge and boundary objects. It sheds new light on how to organize collective, knowledge-based work to produce reliable and innovative designs.