Stabilization of clay materials is of interest to any engineer who must deal with this type of soil. Stabilization techniques can be mechanical or chemical, or both, but the addition of a stabilizing agent is generally the favored approach. Lime in one form or another has been the most widely used stabilization agent for clay. However, portland cement to stabilize clay has been promoted and used in some applications. It was the purpose of this research to define the effectiveness of hydrated lime and portland cement on three Texas clays. Variables evaluated included two levels of treatment, two levels of pulverization, two compaction efforts, two moisture conditions, and a range of curing times. On the basis of the results and conditions of this test program, lime treatment of expansive, high-plasticity soils was more favorable for compressive strength attainment than was cement treatment of these soils. In general, lime treatment produced higher dry-conditioned strengths, but the major advantage was in the wet-conditioned strengths. Lime treatment provided significantly better resistance to moisture damage when these soils were compacted by the modified compactive effort. Cement treatment of low-plasticity sandy clay produced significantly higher compressive strengths than did lime treatment of this soil.