The combination of organic polymers and inorganic particles can lead to a composite material that is more useful than either of the individual components, By careful selection of the particles and polymers, designers can tailor composites to meet final product requirements that might be difficult to achieve using other materials. Currently, there is tremendous interest in forming organic/inorganic composites that are spatially organized on the nanometer length scale. Such nanostructured composites are needed to overcome obstacles to miniaturization as feature sizes in devices reach the nanoscale. In this talk, we describe how to create these composites through self-assembly, where cooperative effects between the different components drive the system to form nanostructured materials. The results can facilitate the fabrication of the next generation catalysts, selective membranes, and photonic band gap materials.