We modeled the reflectance from rough conductive surfaces for both TM and TE polarization. We used a Nystrom technique to solve the Electric Field Integral Equation in the TM case and the Magnetic Field Integral Equation in the TE case. We studied a large number of sample surfaces with varied roughness heights and frequencies from various incident angles and compared these results to the predictions of the Debye Waller model. We determined that the Roughness correction is a function of qh, as is proposed by Debye Waller, where q is 2*pi*sin(theta)/lambda and h is the rms surface roughness height. In addition to the quadratic term predicted, our simulations showed significant linear and cubic terms. These terms are especially significant for high spatial frequency roughness where the spatial frequency is on the order of a wavelength.