In the present study, sand and expanded polystyrene (EPS) geofoam were evaluated as potential stabilizers in improving the swelling behaviour of bentonite. A comprehensive laboratory experimental programme was conducted on bentonite with a high swelling potential. Five dosage levels of sand and five different thickness of EPS geofoam were investigated in two stages of the experiments. In the first stage of testing, the effect of sand on the swelling pressure of bentonite was investigated by two series of experiments. In the first series of experiments, bentonite at optimum water content was mixed with sand in proportions of 20, 40, 60 and 80% by weight. In the second series of experiments, the same percentages of sand were used as in the first series of experiments but the sand and bentonite were not mixed together. The sand was placed on the sample of bentonite which was then compacted at optimum water content. In the second stage of testing, the effect of EPS geofoam on the swelling pressure of bentonite was investigated using different thicknesses of EPS geofoam placed on the sample of bentonite. These thicknesses were the same as the thicknesses of sand which was placed on the sample of bentonite in the second series experiments of the first stage. These experiments show that the expansive soil can be successfully stabilized by sand and EPS geofoam.