A series of undrained, cyclic simple shear tests were performed on reconstituted specimens with various clay contents to study the effects of clay content on liquefaction characteristics of clayey sands based on a framework of an idealized binary packing model and intergrain state parameters. From observed liquefaction characteristics, clayey sands with different clay contents can be grouped as sand-like or clay-like soils depending on the clay content and the transitional fines content of the sand-clay mixture. A simple equation is derived and verified to correlate the transitional fines content with the void ratios of the clean sand and the pure clay consisting of the mixture. In addition, a new relationship for clay content correction is proposed based on the linear relationship between the cyclic resistance ratio and the clay content at the same intergranular void ratio. The cyclic resistance ratio of sand-like clayey sands can be divided into two components: (1) the resistance of the sand skeleton at the specific intergranular void ratio, and (2) the increment of cyclic resistance from clayey fines. The rate of increment for cyclic resistance varies with the properties of contained clay particles. Data from three independent studies have shown the proposed procedure is promising.