The most significant new developments in high energy physics, such as the experimental verification of W+Z<198> <198> particles and new tests of the theory of quark interactions update this Third Edition. Professor Perkins provides a balance between experimental and theoretical concepts, with treatment that is informal and empirical, emphasizing the basic theoretical concepts rather than mathematical detail, and key experiments in the field and how they have influenced our thinking. Key experiments include helicity of the neutrino, electric dipole moment of the neutron, the level spectrum of heavy quark-antiquark states, and deep inelastic scattering of leptons by nucleons.