Approach fills behind bridge abutments are commonly supported by wrap-around mechanically stabilized earth (MSE) walls; however the effect of this geometry on passive force development is unknown. This report describes the first large-scale tests to evaluate passive force-deflection curves for abutments with MSE wingwalls. A test was also performed with fill extending beyond the edge of the abutment wall for comparison. The abutment wall was simulated with a pile supported cap 5.5 ft high, 11 ft wide, and 15 ft long in the direction of loading. The backfill behind the pile cap consisted of clean sand compacted to 96% of the modified Proctor maximum density. As the pile cap was loaded laterally, pressure on the MSE wall led to pull-out of the steel reinforcing grids and the MSE wall panels moved outward about 2% of the wall height when the ultimate passive force developed. Despite pullout, the passive force per effective width was 28 kips/ft for the pile cap with MSE wingwalls compared to 22.5 kips/ft for the cap without wingwalls. Nevertheless, the passive force with the MSE wingwalls was still only 76% of the resistance provided by the cap with fill extending beyond the edges. The pile cap with MSE walls required greater movement to reach the ultimate passive force (deflection of 4.2% of wall height vs. 3%). The Caltrans method provided good agreement with the measured passive resistance while the log spiral method required the use of a higher plane strain friction angle to provide reasonable agreement.