An experimental investigation into the ultimate bearing capacity of the strip footings resting on a sand slope with and without geogrid reinforcement is reported. The parameters investigated are the effect of the depth of the single layer of geogrid, vertical spacing of geogrid layers, number of geogrid layers, length of geogrid layers, the effects of the angle of the slope inclination, the relative density of sand, and type of reinforcement. A group of finite-element analyses was also carried out on a model slope. The results proved that the reinforcement had a considerable effect on the ultimate bearing capacity of the strip footings on a sand slope. The improvement in the bearing capacity of the strip footing on a reinforced slope was found to be strongly dependent on the slope angle, the relative density of sand, and the tensile strength of geogrid reinforcement. A satisfactory agreement between the experimental and numerical test results on a general trend of behaviour and optimum geometry of reinforcement placement is observed. Based on the model test results and the finite-element analyses, optimum values of the geogrid parameters for maximum reinforcing effect are discussed and suggested.