This volume aims to provide a thorough treatment of the phenomena of elastic anisostropy and a discussion on dislocation mobilities. The book presents a wide treatment of these topics, and includes descriptions of detailed theoretical models to describe dislocations and cracks, and moving dislocations. An overview is given of the physical behaviour resulting from dislocation mobility in materials, such as glide and climb, interactions with point defects and the behaviour of dislocations under radiation such as creep and swelling.