In 1984, Nam Sub, who was then the Assistant Director for Engineering at the National Science Foundation (NSF), created the Design Theory and Methodology Program. Among his goals in creating this program were to develop a science of engineering design and to establish design as an accepted field of engineering research. From 1984 to 1986 this program was directed by Susan Finger; from 1986 to the present Jack Dixon has been the director. The program itself has covered a broad range of disciplines, from chemical engineering to architecture, and a broad range of research paradigms, from psychological experiments to mathematical models. The present volume is based on the second NSF Grantee Workshop on Design Theory and Methodology, called Design Theory '88, which was held June 2-5, 1988 at Rensselaer Polytechnic Institute in Troy, NY, USA. It is, however, not strictly a proceedings since it includes some material that was not presented at a the Workshop and since it omits some papers and discussions that were presented at the Workshop. At the Workshop, invited speakers presented overviews of six different research areas based on summaries submitted in advance by the grantees of the Design Theory and Methodology Program. Since most of the speakers were not supported under the NSF program they brought fresh views to it. The other papers in this book were submitted directly to this volume and were not presented at the Workshop.