In this paper we consider the creation of future computer-based design environments to support a team-based preliminary design process. Adopting the view of Bucciarelli [1988], we see design as a social process among the team members. Each team member has his (or her) own view of the artifact to be designed, and each operates in his own "object world." We list a set of attributes we see as needed for a computer-based environment to support this process. After suggesting that the activity of design is a form of continual evolutionary model development by the participants, we argue that it can be captured by providing a support system to record and organize models as they are developed and shared. Based on our work with creating the modeling language ASCEND, we propose a number of specific concepts on which the design of such a support system can be based.