This paper promotes simple criteria based on “key” soil parameters that help partition liquefiable and non-liquefiable silty soils. A brief review of the physical characteristics of silts and clays is first given to help clarify some misconceptions about silty soils. Clay content and liquid limit are then considered as two “key” soil parameters that help partition liquefiable and non-liquefiable silty soils. Several case histories are presented that illustrate the applicability of using clay content as a “key” soil parameter. Attention is drawn to an analogy between the liquid limit and the shear strength of a soil. This analogy is expanded to show that the liquid limit can be regarded as a “key” soil parameter that gives a relative measure of liquefaction susceptibility. Inadequacies of basing criteria for liquefaction of silty soils on just one “key” parameter are finally discussed, leading to the promotion of simple criteria for liquefaction of silty soils, utilising together both the clay content and the liquid limit soil parameters.