Epoxy nanocomposites were prepared from the montmorillonite after organic treatment with a high Tg epoxy resin (Shell Epon 862 and curing agent W). Investigation of the rheological characteristics showed that the addition of clay to the resin did not significantly alter the viscosity or cure kinetics and that the modified resin would still be suitable for liquid composite molding techniques such as resin transfer molding. DSC was performed to study the kinetics of the curing reactions in the modified resin. An in situ small-angle x-ray scattering (SAXS) experiment was used to try to understand the structural development during cure. Based on the in situ SAXS data, structural changes were monitored in real time during cure and analyzed. Results from wide-angle x-ray diffraction, SAXS, and transmission electron microscopy of the polymer-silicate nanocomposites were used to characterize the morphology of the layered silicate in the epoxy resin matrix. The glassy and rubbery moduli of the polymer-silicate nanocomposites were found to be greater than the unmodified resin due to the high aspect ratio and high stiffness of the layered silicate filler. The solvent absorption in methanol was also slower for the polymer-silicate nanocomposites.