This reader-friendly introduction to the theory that underlies the many fascinating properties of solids assumes only an elementary knowledge of quantum mechanics. Taylor and Heinonen describe the methods for performing calculations and making predictions of some of the many complex phenomena that occur in solids and quantum liquids. Their book, aimed at advanced undergraduates and beginning graduate students, leads the reader from the fundamental behavior of electrons and atoms in solids to the most recently explored manifestations of the quantum nature of condensed matter.