The mass specific extinction coefficient and the polarization ratio at 90 degrees of simulated smoke agglomerates are computed for clusters with 3 to 1390 primary spheres and for size parameter from 0.05 to 0.6 using the coupled electric and magnetic dipole (CEMD) method. For the size parameter range of interest for postflame smoke, the specific extinction coefficient computed by CEMD is 21% to 36% greater than Rayleigh prediction, and for this size range for clusters with 100 to 1000 primary spheres, the range in the specific extinction coefficient is about 12%. Agreement between measured and predicted specific extinction coefficient would require selection of a refractive index outside the range of values widely used by the combustion community. The polarization ratio at 90 degrees is found to be a monotonic function of primary sphere size and relatively independent of agglomerate size. Comparison with the limited experimental results indicates potential For polarization ratio as a diagnostic for primary sphere size.