For nearly a century, the absorption coefficient has been used as a measure for the amount of energy lost when sound reflects from a surface. There is now a need for a diffusion coefficient which measures the angular distribution of the reflected energy. Diffusion coefficients enable the worth of diffusing surfaces to be evaluated and in the future could help improve the accuracy of geometric room acoustic modeling. A current investigation is looking at forming a diffusion coefficient that is clearly defined, has physical rigor, is usable in a variety of real life applications, and is easy to measure. The problems associated with finding a single parameter to meet all the above criteria will be discussed. A variety of measures for monitoring the diffusion from unbaffled surfaces will be presented, as well as possible solutions for baffled and large surfaces.