Symposium P, "Deformation Mechanisms, Microstructure Evolution, and Mechanical Properties of Nanoscale Materials," was held Nov. 29-Dec. 3 at the 2010 MRS Fall Meeting in Boston, Massachusetts. This resultant volume addresses the topic of materials used in next-generation technological devices. These devices are used for a variety of applications-ranging from biomedical to space to energy-related-and will be subjected to non-ambient temperatures and high stresses and pressures. A variety of advanced nanomaterials and nanoscaled architectures have been proposed to meet these stringent demands. However, a complete understanding of the mechanisms that govern deformation at these scales is still elusive. This volume focuses on providing the state-of-the-art research on the mechanical response of nano- and microscale components that may comprise these devices and highlights emerging topics in novel mechanical testing techniques, in situ microscopy, high- and low-temperature deformation mechanisms, and mechanical property characterization of materials, as well as recent advances in atomistic and multiscale modeling of nanomaterials.