The first detailed vibrational mode assignments for insulating polystyrene surfaces based on high-resolution electron energy loss spectroscopy (HREELS) are presented. Improvements in energy resolution based on low-energy secondary beam neutralization and spectral restoration algorithms allow an effective resolution of similar to 6 meV (50 cm(-1)) at relatively high loss intensities. This permits the assignment of eighteen vibrational modes for this material which are in good agreement with known IR and Raman bands.