Toughening mechanisms in hard, metal oxide nanoparticle reinforced epoxy systems were analyzed using a multi-scale approach. Samples on varying scales were fabricated using a shear mixing device and the dispersion of the particles was characterized. On the macro-scale, four point bend testing showed an 80 percent increase in fracture toughness over neat resin samples for composites with low filler volume percents. Testing completed within the chamber of a focused ion beam provided insight in to the mechanisms of fracture on the microscale. Further analysis of the results was coupled with finite element analysis to model the material behavior.