The use of stone columns (otherwise called granular piles) has proved to be an economical and technically viable ground improvement technique for construction on soft clay soils. Though the stone columns are designed to carry vertical compressive loads, soil movements occurring in the field conditions may cause shear deformations in the stone columns. The stone columns, particularly installed in very soft soils, may not be able to resist these shear movements because of the low confinement offered by the surrounding soil. The shear load capacity of such stone columns can be significantly improved by encasing the individual stone columns with suitable geosynthetic. The encasement confines the aggregate and makes the stone column act like a semirigid pile; thus leading to increased shear stiffness of the column. This paper discusses some laboratory model tests performed to investigate the shear load capacity of stone columns with and without geosynthetic encasement. The laboratory tests were performed by inducing lateral soil movements in a stone column treated soft soil. The results have shown qualitative improvement in the shear stiffness of the stone column due to geosynthetic encasement. Copyright © 2009 by ASTM International.