This paper presents an evaluation of the soil-geogrid interaction, conducted to quantify the contributions of passive and interface shear mechanisms to the overall pullout resistance of geogrids. An experimental testing program was conducted in this investigation using both large-scale and newly developed individual-rib pullout devices. The large-scale pullout tests were conducted using uneasily coated geogrid specimens with and without transverse ribs. On the other hand, the individual-rib pullout tests were conducted using individual longitudinal and transverse ribs.