QUANTUM THEORY OF SOLIDS is a modern presentation of theoretical solid state physics. It builds directly on the same author's Introduction to Solid State Physics and is planned as a one year graduate course for experimental and theoretical physicists it is well- suited for self study because the text contains 110 problems. The first part of the book treats phonon, electron, and magnon fields, culminating in the BCS theory of superconductivity. The second part considers Fermi surfaces and electron wave functions, and develops the group theoretical description of Brillouin zones. The third part applies correlation functions to time-dependent effects in solids, with an introduction to Green's functions. QUANTUM THEORY OF SOLIDS is a modern presentation of theoretical solid state physics. It builds directly on the same author's Introduction to Solid State Physics and is planned as a one year graduate course for experimental and theoretical physicists it is well- suited for self study because the text contains 110 problems. The first part of the book treats phonon, electron, and magnon fields, culminating in the BCS theory of superconductivity. The second part considers Fermi surfaces and electron wave functions, and develops the group theoretical description of Brillouin zones. The third part applies correlation functions to time-dependent effects in solids, with an introduction to Green's functions.