Concrete masonry is a material with good fire resistance. However, unlike steel, reinforced concrete, and wood materials, there has been little done to improve upon its base fire resistance. The purpose of this research was to understand the fire resistance of existing masonry construction and learn how best to improve upon masonry's fire resistance. First, a literature review was done to determine the effects fire had on concrete, and how this could change with different mix designs and temperature ranges. These included common mixes (such as normal-weight and lightweight concrete) as well as novel mixes (such as fly ash, recycled aggregate, or glass aggregate concrete). As masonry units have different geometries, research was also done to determine the effects different geometries have on the fire resistance of materials. Once this baseline was established, research was done on insulation materials, to determine which materials might be suitable and compatible with concrete masonry. Full scale experimental data was collected to determine how standard masonry units and building techniques reacted to the standard fire. Then new geometries and mix designs were tested to evaluate how the fire resistance was affected by the changes. After experimental data had been collected, thermal models were created in order to validate the experimental results, as well as to determine which masonry units should be tested in the future. Finally, novel concrete mixes were modeled and compared to determine their effect on the fire resistance of concrete masonry walls.