The effect of overburden pressure on liquefaction resistance of sand is studied and results of a site-specific investigation are presented. When estimating liquefaction resistance of sand from the indirect approach using the chart suggested by Seed et al. (1984) a correction factorKσis applied to account for vertical effective overburden stresses larger than 1 tsf. Published data indicate a decrease inKσwith increased confining stress but with a wide range ofKσvalues for the same confining stresses, predicting significantly differing liquefaction resistance. The effect of confining stresses on liquefaction resistance was investigated as part of a comprehensive seismic assessment of Duncan Dam in British Columbia. The results indicate thatKσis dependent on confining stresses and the relative density of the soil, and values are generally significantly higher than much of the previously published data.Key words: liquefaction, sand, confining stress, density, cyclic resistance ratio.