This is the most systematic, comprehensive and up-to-date book on the theoretical analysis of piezoelectric devices. It is a natural continuation of the author s two previous books: An Introduction to the Theory of Piezoelectricity (Springer, 2005) and The Mechanics of Piezoelectric Structures (World Scientific, 2006). Based on the linear, nonlinear, three-dimensional and lower-dimensional structural theories of electromechanical materials, theoretical results are presented for devices such as piezoelectric resonators, acoustic wave sensors, and piezoelectric transducers. The book reflects the contribution to the field from Mindlin s school of applied mechanics researchers since the 1950s. Contents: Three-Dimensional Theories; Thickness-Shear Modes of Plate Resonators; Slowly Varying Thickness-Shear Modes; Mass Sensors; Fluid Sensors; Gyroscopes -- Frequency Effect; Gyroscopes -- Charge Effect; Acceleration Sensitivity; Pressure Sensors; Temperature Sensors; Piezoelectric Generators; Piezoelectric Transformers; Power Transmission Through an Elastic Wall; Acoustic Wave Amplifiers.