The first contemporary text specializing on the dynamic problems of piezoelectric crystal plates for resonant acoustic wave devices (such as resonators, filters, and sensors) since H F Tiersten's publication in 1969. This book provides an up-to-date, systematic and comprehensive presentation of theoretical results on waves and vibrations in quartz crystal plates. It expounds on the application of the theories of elasticity and piezoelectricity in acoustic wave devices made from crystal plates through a coverage spanning from classical results on acoustic wave resonators, up to present-day applications in acoustic wave sensors. This text begins with the exposition of the simplest thickness modes and various frequency effects in them due to electrodes, mass loading, contact with fluids, air gaps, etc., and continues on to the more complicated shear-horizontal modes, as well as straight-crested modes varying along the digonal axis of rotated Y-cut quartz. Modes varying in both of the in-plane directions of crystal plates are also addressed. The analysis within are based on the three-dimensional theories of piezoelectricity and anisotropic elasticity with various approximations when needed. Both free vibration modes (stationary waves) and propagating waves are studied in this text. Forced vibration is also treated in a few places. This book is intended to serve as an informative reference to personnel who employ piezoelectric crystal plates in the course of their profession.