The development of surface alteration layers and solid products in the reaction of borosilicate nuclear waste glass with aqueous solutions has been studied as a function of time, surface morphology, water flow rates, and solution composition. A physical description of the growth of the surface layers has been developed, and several solid reaction products have been identified. The results of the study support a saturation based description of long-term radionuclide release from glass waste forms and demonstrate the complex dependence of short-term leaching experiments upon both surface and solution variables.