Sugarcane bagasse composites have been prepared by the free radical polymerization of regular or modified vegetable oils with divinylbenzene and n-butyl methacrylate in the presence of dried, ground sugarcane bagasse. Various cure times and temperatures have been investigated to determine the optimum cure sequence for the new materials. The postcure time has also been varied, and an ideal postcure treatment of 1 h at 180°C at ambient pressure has given the best overall properties. The effect of varying the filler load and resin composition has been assessed by means of tensile tests, dynamic mechanical analysis, thermogravimetric analysis, Soxhlet extraction, followed by proton nuclear magnetic resonance spectroscopic analysis of the extracts, and scanning electron microscopy. It has been observed that the initial washing and drying of the filler influence the filler–resin interaction and impact the final properties of the composites.