This research supported by grant FG02-86ER45367 is the study of the properties of solids by means of the picosecond technique. In this research we investigate both fundamental problems in phonon physics and lattice dynamics, and we also apply the technique to the non-destructive evaluation of thin-film microstructures. In the experiments a picosecond light pulse is absorbed at a surface, thereby generating an elastic pulse. This strain pulse propagates through the sample, and is detected at a later time by means of a time-delayed probe light pulse. During the past year our research has been concentrated in three main areas. We have made an extensive series of measurements of ultrasonic attenuation as a function of frequency and temperature in glasses. We have succeeded in generating and detecting surface acoustic waves in microstructures with surface gratings and dot arrays, and have performed several experiments to study the structure of thin films and surface layers. The third area is the investigation of heat flow from metal films into dielectric crystals, and the possible observation of second sound. Also included is the proposal for next years work. 7 refs., 3 figs.