Within the last two decades nanocomposite materials have gained in importance not only in the academic world but also for industrial applications. The preparation of hybrid materials composed of inorganic nanoparticles in polymeric matrices allows for the development of completely new materials with unique qualities. For the successful preparation of polymer nanocomposites different techniques have been established, including melt processing, solution casting, and in situ processing techniques. The chapter will review the current progress in nanocomposite processing and will present a section of realized applications focusing on optical properties of transparent nanocomposites and specific features of clay composite materials.