This paper contains the findings of an experimental evaluation on the behavior of common exterior wall assemblies found in residential construction when impacted by bullets fired from a wide variety of firearms of different caliber. Three basic types of exterior wall finises were evaluated: stucco, vinyl siding, and masonry. All the walls were constructed in wood frame, with the exception of one wall, which was constructed using 140mm hollow concrete blocks as the back-up system. The findings of the study have demonstrated that a bullet fired from a .22 caliber firearm, a relatively small and readily available firearm, can consecutively penetrate two walls constructed in wood frame and vinyl siding. Walls constructed with a 90 mm masonry veneer however are effective in stopping bullets fired from a 9mm submachine gun. These preliminary findings are intended to assist both engineers and architects in choosing the appropriate wall materials for structures where gun fire may occur.