In this upper-level text, Professor Tanner introduces the reader to the behavior of electrons in solids, starting with the simplest possible model. Unlike other solid state physics texts, this book does not begin with complex crystallography, but instead builds up from the simplest possible model of a free electron in a box and introduces higher levels of complexity only when the simple model is inadequate. The approach is to introduce the subject through its historical development, and to show how quantum mechanics is necessary for an understanding of the properties of electrons in solids. The author also includes an examination of the consequences of collective behavior in the phenomena of magnetism and superconductivity. Examples and problems are included for practice.