Soil liquefaction is one of the most interesting and intriguing phenomena in geotechnical engineering that has been under research for decades. This is probably because its consequences can be catastrophic with significant socio-economical impacts. Many natural sands in situ which are prone to liquefaction are silty sands because they contain certain amount of silt. The previous laboratory research on liquefaction of silty sands focused on three major aspects: 1)influence of fines content, 2)influence of confining stress,and 3)influence of specimen preparation method. Among those, influence of fines content on liquefaction potential of sands resulted in contradictory conclusions (i.e. whether fines increase or decrease the liquefaction potential) and still debated today. Recent research results have shown that relative size of fines(silt in this case) with respect to sand grains could also be quite important for static liquefaction of silty sands. This project, with three major research objectives, would investigate how silt characteristics including content, gradation, and relative size, influence the liquefaction behavior of silty sands subjected to different loading conditions. In the first two objectives, silt influence on liquefaction caused by static and cyclic loading will be investigated by conducting monotonic and cyclic triaxial compression tests on different silty sands respectively. In the third objective, possible corrections and modifications will be prepared for the necessary sections of the current liquefaction evaluation criteria used by the research and practicing community. The results of this project will expected to be innovative in such a way that they would clarify whether the existence of fines increases, decreases or conditionally influences the liquefaction potential of sands, and what kind of corrections and modifications are needed for some of the current evaluation procedures.