The results of a three-year research program conducted to investigate the settlement and liquefaction of sands under multi-directional shaking are evaluated. The investigation indicated that the behavior of a saturated sand under cyclic loading conditions is a function of its geologic and seismic history and grain structure as well as its placement density. It is concluded that the resistance to liquefaction of a sand deposit can best be estimated by laboratory testing on undisturbed samples. It is shown that cyclic triaxial tests used in conjunction with appropriate correction factors to account for multi-directional shaking, simple shear loading conditions, and overconsolidation effects can provide valid data on cyclic loading characteristics. The concepts of ''limited strain potential'' and acceptable value of the factor of safety against initial liquefaction are introduced. Finally, the two basic methods for evaluating liquefaction potential and the effects of liquefaction are reviewed and updated with the information obtained through this research effort.