This volume contains the proceedings of the Fourth International Conference on Phonon Scattering in Condensed Matter held from August 22-26, 1983 at the University of Stuttgart. The preceding conferences were organized at Saint Maxime and Paris in 1972, at the University of Nottingham in 1975, and at the Brown University Providence/Rhode Island in 1979. The Stuttgart conference, like the preceding conferences, was mainly con cerned with "propagating" high-frequency acoustic phonons, mechanical waves and heat up to the lattice limiting frequency. Lattice dynamics, optical pho nons, phase...