Regulatory compliance requires that soils contaminated with toxic organic and metallic compounds be cleaned up. Several chemical and thermal detoxification technologies are commercially available for directly treating the contaminated soils excavated from contaminated sites. In contrast, soil washing with aqueous solutions transfers the contaminants from the solid matrix to the aqueous fraction which, then, needs to be further treated. Membranes have not been used much for treating these effluents. However, several membrane techniques appear promising. In these techniques, the main objective is to find ways of concentrating the contaminants with much higher volume reduction than is customarily available. Applications of membranes to soil washings should primarily be looked upon as an inexpensive aid to destruction, disposal, or recovery technologies that determine the ultimate fate of the contaminants.