A composite’s strength is determined by the interaction between the fiber and matrix. Since the matrix distributes the load onto and between the fibers it is important to know the respective volume amounts to insure proper load distribution. Studies [1] have been done relating axial tensile and axial compressive strengths to fiber volume fraction (FVF). Current methods to determine FVF are destructive and time consuming. They involve removal of the matrix by heat or chemical digestion. In this work a thermal diffusivity measurement technique is investigated for the characterization of FVF in graphite composite plates. A thermal technique is advantageous since it is noncontacting, fast, and nondestructive.