The use of computer technology in design practice is moving towards a distributed resource available to a team of designers. The development of software to support designers has traditionally been based on the assumption that there will be a single person using the software at a time. Recent developments have enabled the feasibility of software for two or more simultaneous users, leading to the possibility of computer mediated collaborative design (CMCD), where the computer plays the role of mediator and design information handler. There is the potential for the computer to play a more active role in collaborative design through enhanced visibility of 3D models and assistance in generating alternative designs and design critiques. With this potential the computer not only mediates the collaborative design process but actively supports the designers. Research in integrated CAD, multimedia and design database systems, virtual design studios, and design protocol studies provide the basis for a formal study of CMCD. We have developed an experimental methodology to study the difference in design semantics documented using computer applications when designing alone as compared to designing collaboratively. This methodology can be applied to study other aspects of CMCD.