This excellent text, directed to upper-level undergraduates and graduate students in engineering and applied physics, introduces the fundamentals of quantum mechanics, emphasizing those aspects of quantum mechanics and quantum statistics essential to an understanding of solid-state theory. A heavy background in mathematics and physics is not required beyond basic courses in calculus, differential equations, and calculus-based elementary physics. The first three chapters introduce quantum mechanics (using the Schrödinger equations), quantum statistics, and the free-electron theory of metals. Chapters 4 and 5 deal with the WKB approximation and perturbation theory. Chapters 6 and 7 focus on the periodic potential of a crystalline solid and electronic energy bands. To increase the effectiveness of the material as a learning aid, all developments are carefully worked out, complete details are given for each of the derivations, and successive derivations are developed on a firm basis provided by the preceding material. Throughout the text, examples from solid-state physics illustrate specific applications and demonstrate the principal results that can be deduced by means of quantum theory. Numerous problems (with selected answers), projects, and exercises have been incorporated to facilitate mastery of the text material.