Composites of poly methylmethacrylate containing quartz particles and glass beads have been prepared over a range of filler contents. Organosilicon compounds (silanes) have been employed as bonding agents between filler and matrix. To study the reactions between silane and filler, model experiments have been performed on fumed silica surfaces using infra red spectroscopy. Modulus, flexural strength and compressive strength of composites have been determined as a function of volume fraction of filler.