We describe a comprehensive model for the optical properties of pristine films of poly-(3-hexylthiophene) (P3HT). The presented model is anisotropic with the optical axis normal to the substrate plane, which is consistent with previous x-ray diffraction studies that show preferential edge-on packing of the polymer chains on the substrate. Peak locations and spacings are defined using a Huang-Rhys vibronic progression consistent with known phonon energies. We demonstrate that the model fits variable-angle spectroscopic ellipsometry and normal-incidence transmission data well, and accurately predicts angle-and polarization-dependent transmission and reflection data. The spectral features of the optical constants used in the model are in excellent agreement with published spectroscopic data on P3HT. (c) 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 186-194, 2011