Functional Methods and Models in Quantum Field Theory presents a unified description of the major soluble and approximate models of relativistic quantum field theory. The first half offers a compact expression and derivation of functional methods applicable to relativistic quantum field theory. The second part addresses the models themselves, employing elegant functional techniques to describe nearly all the soluble and approximate models of field theory. The level of presentation is such that students familiar with conventional field theoretic arguments should make the transition to a functional description without difficulty. Topics addressed in Part I include the generating functional and the S-matrix, construction of the generating functional, noncanonical (chiral) generalizations, and special topics in quantum electrodynamics. Part II covers perturbation expansions, soluble models, no-recoil methods, relativistic eikonal physics, and speculations at high energy. This edition features a new Preface by author H. M. Fried.