This article describes two mathematical formalisms for the determination of the second and fourth order parameters of molecular films using optical spectroscopy. Method A uses polarized total internal reflection fluorescence (TIRF) to calculate the second and fourth order parameters, < P-2(cos theta)> and < P-4(cos theta)>, using an independently determined value for the angle between the absorption and emission dipoles, gamma. Method B uses < P-2(cos theta)> obtained from attenuated total reflectance (ATR) data, along with polarized TIRF measurements to calculate < P-4(cos theta)> and < cos(2) gamma >. The choice of a specific method should rely on experimental considerations. We also present a method to separate the contributions of substrate surface roughness and dipole orientation with respect to the molecular axis from the spectroscopically determined second and fourth order parameters. Finally, a maximum entropy approach for construction of an orientation distribution from order parameters is compared with the commonly used delta and Gaussian distributions.