Mechanical properties of crystalline materials are almost always dominated by the defects within them. The ability to shape metals into pipes, girders and furniture stems from the generation, motion and interaction of these defects. Defects are also the agents of chemical changes within crystals, enabling mass transport by atomic diffusion and changes of phase. Defects distort the crystal and these distortions enable defects to interact over large distances. The theory of elasticity is used to describe these interactions. Physics of Elasticity and Crystal Defects, 2nd Edition introduces the reader to linear elasticity and its application to point defects, dislocations, inclusions and cracks. It argues that current theories of the transition cannot account for many experimental observations, leaving many technologically important questions unanswered. A unique feature of the book is the attention given to the atomic structure of defects and its influence on their properties and their elastic fields. A new chapter on the ellipsoidal inclusion has been included in this second edition. It is applied to the elastic fields of a slip band, which are used in the discussion of work hardening in the final chapter. There are exercises to help the student check their understanding as they work through each chapter. The student is guided through more advanced problems at the end of each chapter with detailed solutions to all exercises and problems included. The last chapter describes five technologically important areas requiring fundamental research, with suggestions for possible PhD projects. This textbook is written for graduate and postgraduate students in physics, engineering and materials science. It is very likely that even those students with some knowledge of elasticity and defects will find much that is new to them in this book.