The Fourth Conference on Fibrous Composites in Structural Design was a successor to the First-to-Third Conferences on Fibrous Composites in Flight Vehicle Design sponsored by the Air Force (First and Second Conferences, September 1973 and May 1974) and by NASA (Third Conference, November 1975) which were aimed at focusing national attention on flight vehicle applications of a new class of fiber reinforced materials, the advanced com posites, which afforded weight savings and other advantages which had not been previously available. The Fourth Conference, held at San Diego, California, 14-17 November 1978, was the fi rst of these conferences to be jointly sponsored by the Army, Navy and Ai r Force together with NASA, as well as being the first to give attention to non-aerospace applications of fiber reinforced composites. While the design technology for aerospace applications has reached a state of relative maturity, other areas of application such as mi litary bridging, flywheel energy storage systems, ship and surface vessel components and ground vehicle components are in an early stage of development, and it was an important objective to pinpoint where careful attention to structural design was needed in such applications to achfeve maximum structural performance payoff together with a high level of reliability and attractive economics.