A molecular approach to the fundamentals of viscoelastic behavior in polymers, bridging the gap between introductory accounts and advanced research level monographs. This second edition includes new coverage of the theory of reptation, the kinetic theory of rubber elasticity, and an entirely new chapter on dielectric relaxation. Presents all derivations in detail, and treats concepts and models paying special attention to assumptions, simplifications and limitations. Provides problems at the end of each chapter.