A lateritic soil classified as sandy clay or (CL) and A-7-6 (5) according to Unified Soil Classification System (USCS) and AASHTO classification system respectively,was treated with up to 10% pulverized steel slag (an industrial waste product) by dryweight of soil. Elemental and chemical analysis of the steel slag was determined using x-ray fluorescence spectroscopy. Tests were carried out to determine the index properties, compaction characteristics (maximum dry density, MDD and optimum moisture content, OMC), strength characteristics (California bearing ratio, CBR and unconfined compressive strength, UCS) and permeability of the natural and treated soil. Test results show that Atterberg limits (liquid limit, plastic limit and plasticity index) generally decreased, while specific gravity of soil ” steel slag mixtures increased with higher steel slag content; MDD and OMC increased and decreased, respectively, with higher steel slag content. Generally, CBR and UCS increased up to 8% steel slag treatment of the soil. Permeability of soil ” steel slag mixtures increased with higher steel slag content. Based on laboratory test results, an 8 % optimal stabilization of the A-7-6 soil with steel slag satisfactorily meets the Federal Republic of Nigerian General Specifications (Roads and Bridges) requirement for subgrade materials.