Wave optics, geometrical optics, and partial coherence approaches for the calculation of radiative properties of single and multilayer thin films with arbitrary angles of incidence are presented with emphasis on the partial coherence approach. Solution methodologies are compared and a partial coherence approach is shown applicable over the entire range of film sizes. The effects of film thickness, angle of incidence, polarization, and bandwidth of radiation on radiative properties of single films is demonstrated. Hemispherical reflectance is used to typify gross film radiative properties over all angles. Multilayer film theory is employed to examine the effect of substrate thickness for a case of interest. Proposed regime limits are investigated using simple material models and a typical regime map delineating thick and thin films is presented.