To improve the performance of rubber compounds using precipitated silica as a reinforcing filler, the silica surface was directly modified by (1) adsorption of a surfactant, (2) adsolubilization of an organic monomer, (3) in situ polymerization of the monomer in the surfactant bilayer, and (4) partial surfactant removal. Silica was thus surface modified with polymerized styrene, isoprene, butadiene, and copolymers. Styrene-butadiene modification afforded the most promising candidate based on evaluation in a silica-filled model tire compound. Compound physical testing showed that cure times were decreased, and break strength, tear energy, elongation to break, and cut growth resistance were increased. Thus, surface modification of silica by the in situ polymerization of organic monomers affords unique materials useful in improving rubber cure properties and cured compound physical properties.