This report is the second in a two-part series to provide engineers with the necessary background knowledge of Geosynthetic Reinforced Soil (GRS) technology and its fundamental characteristics as an alternative to other construction methods. It supplements the interim implementation manual (FHWA-HRT-11-026), which outlines the design and construction of the GRS Integrated Bridge System (IBS). The research behind the proposed design method is presented along with case histories to show the performance of in-service GRS-IBS and GRS walls.