Three soils: a processed kaolinite, a pulverized shale used as a liner material, and a residual clay soil used as a liner material were compacted using the standard Proctor method and permeated with distilled, deionized water in flexible-wall permeameters. Specimens were subjected to freezing and thawing in an environmental chamber. After being thawed the specimens were again permeated in the flexible-wall permeameters. The freeze/thaw process increased the permeability in all three soils. The kaolinite and residual clay soil showed increases in permeability ranging from one to two orders of magnitude above the pre-freeze/thaw values. The permeability of the pulverized shale increased by less than a factor of three. Post-freeze/thaw permeation at progressively higher effective confining stresses reversed the increase in permeability and resulted in decreasing the permeability from the post-freeze/thaw values. This reduction in permeability was greatest for the kaolinite and the residual clay (one to two orders of magnitude); it was the least for the pulverized shale (maximum of a factor of about two). The results of this study indicated that the magnitude of the change in permeability of specimens subjected to freeze/thaw increased with increasing plasticity of the soils. These findings are in agreement with previous literature that freezing and thawing do increase the permeability of a soil but that the increase can be reduced when effective stress on the soil is increased.