A new type of mechanically improved rubbery epoxy composite is demonstrated based on the use of a mesocellular silica foam, denoted MSU-F, as the reinforcement agent. The silica exhibits a surface area of 540 m(2) g(-1), a cell size of 26.5 nm (14.9 nm window size) and a pore volume of 2.2 cm(3) g(-1). Most notably, the silica foam particles readily disperse in the epoxy matrix without the need for an organic surface modifier or dispersing agent. Relative to the pristine polymer, the tensile modulus, strength, strain-at-break, and toughness for the mesocomposites are systematically enhanced at relatively low silica loading over the range 1-9 wt %. Moreover, all of these benefits are realized without a sacrifice in thermal stability or optical transparency of the polymer. The results demonstrate that silica in mesocellular foam form can provide polymer reinforcement far beyond the level realized for non-porous silica or silica with small mesopores at the same weight loading.