Many previous researchers have used high surface area silica as a model substrate for glass. In this study, the electrokinetic behavior of natural silica and glasses of various compositions have been measured. In all cases, the unmodified samples were found to have points-of-zero charge values between pH 2 and 3.3. Also, the electrokinetic behavior of the samples after the adsorption of an amino-organofunctional silane coupling agent was investigated. For these samples a reversal of the zeta potential occurred, causing the silica and glass samples to possess a net basic surface. Finally, the electrokinetic responses of silica and a glass sample were compared after the adsorption of aluminum metal ion species. The adsorbed metal ion species caused a reversal in the zeta potential at approximately pH 3 for both the silica and the glass samples. In all cases, despite wide variations in the bulk compositions of the silica and glass samples, the electrokinetic behavior was found to be almost identical. Thus, the electrokinetic results found herein support the practice of using silica as a model substrate for glass.