Derived from a course given at the University of Maryland for advanced graduate students, this book deals with some of the latest developments in our attempts to construct a unified theory of the fundamental interactions of nature. Among the topics covered are spontaneous symmetry breaking, grand unified theories, supersymmetry, and supergravity. The book starts with a quick review of elementary particle theory and continues with a discussion of composite quarks, leptons, Higgs bosons, and CP violation; it concludes with consideration of supersymmetric unification schemes, in which bosons and leptons are considered in some sense equivalent. The second edition is updated and corrected and contains new chapters on recent developments. From reviews of the first edition: "This book captures the exciting developments of grand unification and supersymmetry of fundamental interactions in quantum field theory... gives a self-contained field-theoretic treatment of the complete subject... almost every possible development is included here." #Mathematical Reviews#1.