The structure and dynamics of filler nanoparticles and macromolecules in polymer nanocomposites determine many aspects of macroscopic behavior, which is why these properties have attracted considerable interest in the scientific literature. In this article, recent progress using scattering techniques for the elucidation of structure and dynamics, of both filler nanoparticles and polymer chains, is reviewed. Small-angle X-ray and neutron scattering, more and more combined with direct imaging methods and simulations, are appropriate methods to investigate nanocomposite structure. While they can usually be applied to standard samples for filler structure, chain structure can only be accessed with neutrons and isotopic substitution, under the zero-average contrast condition to match the filler contribution. Quasi-elastic neutron scattering and X-ray photon correlation spectroscopy cover different time scales with spatial resolution in the nanoscale. The former allows studies of polymer motions from atomic or segmental relaxation to reptation of the entire chain in presence of filler, while the latter is increasingly used for investigations of nanoparticle dynamics.