Complete, systematic, self-contained...the usefulness and scope of application of such a work is enormous...combines thorough knowledge with a high degree of didactic ability and a delightful style." ? Mathematical Reviews In a relatively simple presentation that remains close to familiar concepts, this text for upper-level undergraduates and graduate students introduces the modern developments of quantum field theory. Starting with a review of the one-particle relativistic wave equations, it proceeds to a second-quantized description of a system of n particles, demonstrating the connection of this approach with the quantization of classical field theories. An examination of the restriction that symmetries impose on Lagrangians follows, along with a survey of their conservation laws. An analysis of simple models of field theories establishes the models? content, and the problematic aspects of quantized field theories are explored. Succeeding chapters present the Feynman-Dyson perturbation treatment of relativistic field theories, including an account of renormalization theory, and the formulation of field theory in the Heisenberg picture is discussed at length. The book concludes with an account of the axiomatic formulation of field theory and an introduction to dispersion theoretic methods, in addition to a set of problems designed to acquaint readers with aspects of field theory not covered in the text.