This open access book presents the novel concept of plaston which accounts for the high ductility or large plastic deformation of emerging highperformance structural materials including bulk nanostructured metals heteronanostructured materials metallic glasses intermetallics and ceramics.The book describes simulation results of the collective atomic motion associated with plaston by computational tools such as firstprinciple methods with predictive performance and largescale atomdynamics calculations. Multiscale analyses with stateofthe art analytical tools nanomicro pillar deformation and nanoindentation experiments are also described. Finally through collaborative efforts of experimental and computational work examples of rational design and development of new structural materials are given based on accurate understanding of deformation and fracture phenomena.This publication provides a valuable contribution to the field of structural materials research.