This study presents results from a number of glass fiber reinforced gypsum (GFRG) wall specimens that were monotonically tested at an angle of 45 degrees and under increasing vertical load. Several infill configurations are considered to see possible changes in strength, stiffness, and failure modes. Eight samples with 770 mm x 770 mm x 124 mm side dimensions were prepared to be used in the diagonal shear tests. Concrete and steel reinforcement (rebar) elements were added to the system to achieve the required strength, stiffness, and ductility. C25 concrete grade and empty set12 steel deformed rebars with a steel grade of S420 were used in these samples. The samples were forced to collapse under a monotonically increasing load. Overall behavior was observed and behavioral values such as ultimate shear strength and initial wall shear rigidity/stiffness values were determined. Related load-deflection curves are given. According to the data that were gathered from the experiments, unfilled specimens and specimens filled with concrete at the middle or edge cells had load capacities around (70-85) kN, while fully concrete filled specimens achieved capacities up to (260-270) kN. Experimental results show that filling the edge or middle cells with concrete (i.e. sort of partial filling) has no significant effect on shear capacity when compared to unfilled samples. Crack patterns developed especially within the unfilled cell regions. The fully concrete filled panel, on the other hand, had a significant impact (approximately 3-4 times) on the capacity when compared with the unfilled case. The rebars used in the fully filled samples had no significant effect mainly from the occurrence of separation between the concrete core and GFRG panel for this type of loading but it increased initial stiffness. When the whole system is compared, concrete filling and rebar increase the initial stiffness of the sample. Filling the edge or middle cells with concrete (with and without rebar) has increased the initial stiffness between (1.17-1.47) times when compared to unfilled samples. Fully concrete filled panel (with and without rebar) had a significant impact (1.97-3.66 times) on initial stiffness when compared with the unfilled samples.