DESC: This volume treats Lagrange's equations for electromechanical systems, including piezoelectric tranducers and selected applications. It is essentially an extension to piezoelectric systems of the work by Crandall et al.: Dynamcs of Mechanical and Electromechanical Sysyems, McGraw-Hill, published in 1968. The first three chapters contain classical meterial based on this and other well-known standard texts in the field, such as Methods of Analltical Dynamics by L. Meirovitch, McGraw-Hill, 1970. Some applications are new (e.g. geophone). Chapters 4 to 6 consist of new material which has not been published in a mongraph before. They deal with piezoelectric systems in a unified way, starting from a lagrangian approach.