This volume treats Lagrange equations for electromechanical systems, including piezoelectric transducers and selected applications. It is essentially an extension to piezoelectric systems of the work by Crandall et al.:"Dynamics of Mechanical and Electromechanical Systems", published in 1968. The first three chapters contain classical material based on this and other well known standard texts in the field. Some applications are new and include material not published in a monograph before.