Octafunctionalized silsesquioxanes [(RSiO!.5)8, cubes] offer potential as rigid, hard nanoplatforms to which a variety of organofunctional groups can be appended. Crosslinking these groups leads to novel organic/inorganic nanocomposites that consist primarily of interfacial interactions. These materials can be 100% interphase. We present efforts to develop nanocomposite materials that consist of both continuous and discontinuous organic/inorganic phases. We then discuss methods of probing the properties of these materials. INTRODUCTIONTwo general principles are often used to describe the origin of macroscopic properties in materials. The first is, "Intrinsic materials properties and processing taken together define microstructure." The second is,"Intrinsic materials properties and microstructure together define global properties."With the advent of chemical processing of materials, one can often replace the term microstructure with nanostructure.A less encompassing general principle is that "Control at the finest scales gives the highest homogeneity, thereby providing the highest reproducibility, predictability and ability to tailor properties." This principle is less encompassing because we often would like to prepare materials with "controlled heterogeneity," ie. composite materials. We may generally describe composites as materials that combine two (or more) materials and microstructures. In composite manufacture, the goal is usually to achieve properties that are more than the sum of the properties of the individual components; however, it is often possible to estimate the properties of typical composites using the rule of mixtures. The utility of the rule of mixtures in predicting properties is greatly diminished when applied to nanocomposites.