<p>Current design guidelines for Back-to-Back Mechanically Stabilized Earth Walls (BBMSEWs) are limited, with the Federal Highway Administration technical report providing only a concise overview of their design. In this paper, the behavior of closely spaced connected and unconnected BBMSEWs under applied static loads was numerically investigated using two-dimensional finite element analysis. This study examined the influence of reinforcement arrangement and applied static surcharge loads on BBMSEWs performance by analyzing four numerical wall models with different configurations of geosynthetic reinforcement under various surcharge intensities. For comparison, the factor of safety and horizontal wall displacements were used to assess external stability, while the maximum tensile load in reinforcement was selected to evaluate internal stability. The main findings indicated that reinforcement arrangement has a significant impact on the performance of BBMSEWs and governing their stability. The connected walls exhibited nearly one-half lower horizontal displacements compared to their unconnected walls. The factor of safety showed a substantial variation depending on the connectivity configuration. Additionally, the maximum tensile load in reinforcement decreased by approximately one quarter under the optimal configuration which lower half layer reinforcements of the wall are unconnected while the four upper strips are connected compared to the opposite arrangement.</p>