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.