The development of the supersymmetry technique has led to significant advances in the study of disordered metals and semiconductors. The technique has proved to be of great use in the analysis of modern mesoscopic quantum devices, but is also finding applications in a broad range of other topics, such as localization and quantum chaos. This book provides a comprehensive treatment of the ideas and uses of supersymmetry. The first four chapters of the book set out the basic results and some straightforward applications of the technique. Thereafter, a range of topics is covered in detail, including random matrix theory, persistent currents in mesoscopic rings, transport in mesoscopic devices, localization in quantum wires and films, and the quantum Hall effect. Each topic is covered in a self-contained manner, and the book will be of great interest to graduate students and researchers in condensed matter physics and quantum chaos.