This book combines the proceedings of Mechanical Behavior of Nanomaterials - Experiments and Modeling, and Plasticity in Confined Volumes - Modeling and Experiments. These two symposia brought together researchers to exchange ideas about the mechanical behavior of materials where size, be it microstructural or geometric, plays an important role. Firstly it focuses on understanding the mechanical behavior of nanostructured materials, such as nanoscale thin films, nanowires, nanotubes, and nanoparticles, as well as nanoporous, nanograined and nanotwinned materials. Such materials with submicron length scales are important building blocks for next-generation functional devices and materials systems. The second focus is on understanding how micron and submicron external and internal microstructural-length scales play a defining role in the strength and ductility of a material. Modern simulation methods have revealed a diverse range of atomic and mesoscale processes that can contribute to the emergent plasticity of such complex materials. Topics include: nanostructured materials; polymers and composites; simulations and modeling and microcompression and nanoindentation.