Abstract : The reaction products of a kaolin and a montmorillonrite treated with various alkali and alkaline earth hydroxides, compacted at optimum moisture content and density, and moist-cured for extended times to one year, have been examined. Identification of new mineral phases from X-ray diffraction lines has been considerably simplified by computer search procedures; nevertheless, it is seldom possible to achieve unambiguous X-ray identification due to the pattern similarities of many closely related silicates and alumino-silicates. As an aid to resolving such ambiguities, electron microscopy and electron diffraction have been applied. The latter techniques also have limitations, but all three methods in conjunction with other data provide significant new evidence of the path and end products for alkali-clay stabilization reactions. These reactions are now shown to involve substantial degradation of the clay only in certain instances, and chiefly at the surfaces of clay fabric units. From this work, it is now possible to state the general requirements for a successful inorganic stabilizing reagent. (Author)