Copolymerizations of styrene and the polyhedral oligomeric silsesquioxane (POSS)-styryl macromonomer 1-(4-vinylphenyl)-3,5,7,9,11,13,15-heptacyclopentylpentacyclo [9.5.1.1(3,9).1(5,15).1(7,13)] octasiloxane have been performed with CpTiCl3 in conjunction with methylaluminoxane. Random copolymers of syndiotactic polystyrene (sPS) and POSS have been formed and fully characterized with H-1 and C-13 NMR, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. NMR data reveal a moderately high syndiotacticity of the polystyrene backbone consistent with this use of CpTiCl3 as a catalyst and POSS loadings as high as 24 wt % and 3.2 mol %. Thermogravimetric analysis of the sPS-POSS copolymers under both nitrogen and air shows improved thermal stability with higher degradation temperatures and char yields, demonstrating that the inclusion of the inorganic POSS nanoparticles makes the organic polymer matrix more thermally robust. The polymerization activity and thermal stability are also compared with those of reported atactic polystyrene-POSS copolymers.