Problem solving in physics is not simply a test of understanding of the subject, it is an integral part of learning it. In this book, the key ideas of quantum mechanics are well illustrated by a carefully chosen set of problems complete with detailed, step-by-step solutions. Beginning with a chapter on orders of magnitude, a variety of topics is then covered, including the mathematical foundations of quantum mechanics, Schrödinger's equation, angular momentum, the hydrogen atom, the harmonic oscillator, spin, time-independent and time-dependent perturbation theory, the variational method, multielectron atoms, transitions and scattering. Throughout, the physical interpretation or application of certain results is highlighted, thereby providing useful insights into a wide range of systems and phenomena. There is considerable emphasis on applications to atomic, nuclear, and solid-state physics and this book will be invaluable to a wide range of physics undergraduates.