Volume 51 of Reviews in Mineralogy and Geochemistry highlights some of the frontiers in the study of plastic deformation of minerals and rocks. This book reviews large-strain shear deformation and deformation experiments under ultrahigh pressures; the issues of deformation of crustal rocks and the upper mantle; the interplay of partial melting and deformation; the new results of ultrahigh pressure deformation of deep mantle minerals; the stability of deformation under deep mantle conditions with special reference to phase transformations and their relationship to the origin of intermediate depth and deep-focus earthquakes; a detailed description of fracture mechanisms of ice; of experimental and theoretical studies on seismic wave attenuation; the relationship between crystal preferred orientation and macroscopic anisotropy; recent progress in poly-crystal plasticity to model the development of anisotropic fabrics both at the microscopic and macroscopic scale; a thorough review of seismic anisotropy of the upper mantle covering the vast regions of geodynamic interests and the theoretical aspects of shear localization. All chapters contain extensive reference lists to guide readers to the more specialized literature. This volume was written for a workshop, in December 2002 in Emeryville, California.