Magnetism in the Solid State : An Introduction This book presents a phenomenological approach to the field of solid state magnetism. After introducing the basic concepts from statistical thermodynamics and electronic structure theory the first part discusses the standard models for localized moments (Weiss Heisenberg) and delocalized moments (Stoner). This is followed by a chapter about exchange and correlation in metals again considering the results for the localized and delocalized limit. The book ends with a chapter about spin fluctuations which are introduced as an alternative to the finite temperature Stoner theory. A useful reference work for researchers this book will also be a valuable accompaniment to graduate courses on magnetism and magnetic materials. A Historical Introduction Consequences of Fermi Statistics Paramagnetism Energy Bands in the Crystal Experimental Basis of Ferromagnetism Weiss Molecular Field Model Heisenberg Model Itinerant Electrons at 0 K Band Gap Theory of Strong Ferromagnetism Magnetism and the Crystal Structure — Covalent Magnetism Magnetic Impurities in an Electron Gas Itinerant Electrons at T > 0: A Historical Survey Hubbard Model Landau Theory for the Stoner Model Coupling Between Itinerant and Localized Moments Origin of the Molecular Field Exchange and Correlation in Metals Spin Fluctuations Single Particle Excitations Versus Spin Waves Landau Ginzburg Model for Spin Fluctuations Conclusion and Lookout.