One half of electricity generated in USA is produced from combustion of coal. One of the by-products from this process is fly ash. Because of the increasing cost of landfilling and interests in sustainable construction, electric utilities are searching for methods to beneficially use fly ash. Research has shown that many cementitious fly ashes can be used to stabilization highway subgrades, increasing strength and stiffness and reducing construction costs. Stabilization can also be conducted rapidly and at low cost compared with other methods (preloading, removal and replacement, etc.) The objective of this study is to evaluate how the stiffness and strength of soils stabilized with fly ash are affected by freeze and thaw cycling. Resilient modulus and unconfined compression tests are being conducted on stabilized soils that have been subjected to freeze-thaw cycling.