The title of this Symposium “Newer Structural Materials for Aerospace Vehicles,” is, I think, adequately expressive. We are experimenting here with the idea of giving a broad brush treatment to a variety of materials which are believed by many to have an important future as structural materials in aerospace vehicles. None of these materials are available today as “off-the-shelf” items, and not even on a special order basis. In aerospace environments, a host of new design requirements must be successfully determined and then solved by optimization of many materials to design a vehicle structure with 99.9 per cent reliability. The factors of tremendous cost of advanced structures and protection of human life with reliability in space vehicles requires knowledge of a whole new spectrum of materials properties as compared to the relatively narrow band of property requirements required for the subsonic low-altitude aircraft.