In the light of recent research showing that expanded polystyrene (EPS) geofoam inclusions possess the ability to reduce lateral earth forces on rigid nonyielding retaining walls, this study investigates the potential application of geofoam as a compressible inclusion behind yielding flexible retaining walls. In this context, results of static physical tests on a 0.7m high cantilever retaining wall with dry cohesionless backfill were addressed. In the physical modeling study, wall deflections and lateral earth pressures were monitored to investigate the effect of EPS geofoam inclusion on the behavior of cantilever wall models. It was found that an increase in wall flexibility resulted in a decrease in the load reduction efficiency of the geofoam inclusion since the active stress conditions may already be achieved in the retained soil mass due to lateral wall deflections. However, the geofoam inclusion still provides an additional reduction of lateral force and flexural deflections of the cantilevered flexible walls due to the arching effect induced in the retained soil mass by the lateral compression of the geofoam panel occurring predominately in the lower mid-height of the wall stem.