Abstract: This talk examines ways to use nanoporous materials to address complex materials problems, focusing on how nanoscale porosity can modify the structure and mechanical properties of materials. In electrochemical energy storage, nanoscale porosity produces a desirable combination of electrical connectivity, electrolyte access to the interior of the material, and very short solid-state diffusion lengths for lithium ions, all of which facilitate fast charging. More importantly, using operando diffraction, many nanoscale materials show suppression of the intercalation-induced phase transition that can cause kinetic limitations in bulk materials. Porous architectures can also be used to increase stability in high-capacity, large-volume-change alloy-type anode materials. Here, transmission X-ray microscopy is used to directly image strain related changes in the pore structure itself upon cycling. Finally, in a very different system — multiferroic composites — porosity is used to simultaneously facilitate mechanical coupling between ferromagnetic and ferroelectric components of the materials and to tune mechanical stiffness.