Book excerpt: The IUTAM Symposium on Constitutive Relation in High/Very High Strain Rates (CRHVHSR) was held October 16 - 19, 1995, at Seminar House, Science University of Tokyo, under the sponsorship of IUTAM, Japan Society for the Promotion of Science, The Commemorative Association for the Japan World Exposition (1970), Inoue Foundation for Science, The Japan Society for Aeronautical and Space Sciences, and Science University of Tokyo. The proposal to hold the symposium was accepted by the General Assembly of IUT AM held in Haifa, Israel, in August 1992, and the scientists mentioned below were appointed by the Bureau of IUTAM to serve as members of the Scientific Committee. The main object of the symposium was to make a general survey of recent developments in the research of constitutive relations in high and very high strain rates and related problems in high velocity solid mechanics, and to explore further new ideas for dealing with unresolved problems of a fundamental nature as well as of practical importance. The subjects covered theoretical, experimental, and numerical fields in the above-mentioned problems in solids, covering metals, polymers, ceramics, and composites. Emphasis was given to the following fields: 1. Material characterization of solids in high velocity deformation, experimental techniques, typical data obtained by these techniques, modeling, and constitutive relations 2. Strain rate dependent elasto-visco-plastic stress waves 3. Crack initiation, propagation, and dynamic fracture toughness 4. Dynamic stress concentration 5. Structural dynamics in impact and constitutive relations of solids 6.