The interaction between soils and geosynthetics has a decisive importance in applications of these materials as reinforcement in geotechnical structures. This paper presents the results of a laboratory study involving direct shear, inclined plane and pullout tests carried out to characterise the interface between a granite residual soil, compacted to different relative densities, and a uniaxial geogrid under monotonic and cyclic loading conditions. Test results have revealed that soil density has a remarkable influence on the soil-geogrid interface behaviour. From the comparison of the interface strength properties estimated from inclined plane and direct shear tests, it was found that the extrapolation of the direct shear strength envelope for normal stresses below the tested range may be nonconservative. The pullout tests indicated that the confined tensile strength of the geogrid may be considerably lower than its in-isolation tensile strength. The results from the tests carried out under cyclic loading conditions showed that the cyclic loading may lead to the degradation of the interface strength, which should be taken into account in the design of geosynthetic-reinforced soil structures under repeated loadings.