Recent progress in the study of nonlinear wave propagation has been influenced by developments in mechanics, acoustics, hydro­ dynamics, plasma physics and many other fields of physics. This vast field of research has also given rise to fascinating mathe­ matical ideas: the inverse scattering method and the technique of exterior differential forms being just some to be mentioned. Obviously the theory of nonlinear waves may be interpreted as an interdisciplinary study with the mechanics of continuous media as a theoretical basis. This was the starting point of the proposal to the General Assembly of the IUTAM to hold an IUTAM Symposium on this topic, made by the USSR National Committee of Theoretical and Applied Mechanics and the Academy of Sciences of the Estonian SSR. Actually the IUTAM Symposium on Nonlinear Deformation Waves was the third meeting of such kind to be held in Tallinn. In 1973, the Academy of Sciences of the Estonian SSR and Gorky State University or