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 third edition has been completely revised and brought up to date, particularly by including discussions of the many experimental developments in recent years.