The study of chaos is today one of the most active and prolific areas in atomic physics. This book describes the manifestations of chaos in atoms and molecules, and is an introduction to this fascinating area. The first part of the book deals with the theory and principles of classical chaos, which are then applied to actual atomic and molecular physics systems in the second part of the book. The book covers microwave-driven surface state electrons, the hydrogen atom in a strong microwave field, the kicked hydrogen atom, chaotic scattering with CsI molecules and the helium atom. The book contains many diagrams and a detailed reference list.