Mechanics: Classical and Quantum is a 13-chapter book that begins by explaining the Lagrangian and Hamiltonian formulation of mechanics. The Hamilton-Jacobi theory, historical background of the quantum theory, and wave mechanics are then described. Subsequent chapters discuss the time-independent Schrödinger equation and some of its applications; the operators, observables, and the quantization of a physical system; the significance of expectation values; and the concept of measurement in quantum mechanics. The matrix mechanics and the "hydrogenic atom", an atom in which one electron moves under the influence of a nucleus of charge that, to a very good approximation, can be thought of as a point, are also presented. This book will be very useful to students studying this field of interest.