We compare two methods for obtaining structural information on Langmuir-Blodgett films from polarized infrared spectroscopy. For sufficiently uniform films, we have already shown (refs 11 and 12) that all polarized spectroscopic properties could be characterized by a single quantity that we call the "electrical surface susceptibility tensor", <(gamma)over tilde>. The imaginary parts of the susceptibility tensor could be readily obtained from reflectance measurements with the electric field parallel (Im(gamma(t))) and perpendicular (Im(gamma(n))) to the plane of the film, independently of any specific properties of the film. This, in turn, could be related to the characteristics of individual molecules comprising the film, and their geometric disposition if the molecules are assumed to be interacting dipoles, which corrects, to a large extent, for the local field effects. We report the results of an infrared study performed on a dipalmitoylphosphatidylethanolamime monolayer. Attenuated total reflection spectra for both s and p polarization were recorded, and the spectra of Im(gamma(t)) and Im(gamma n), as well as those of the imaginary part of the refractive index (k(t) and k(n)), ark presented. Finally, the information deduced from the Im(gamma(x)) and k(x) (x = s, p) are compared, and the molecular orientation is discussed both in terms of Im(gamma(x)) and k(x). We show that by using this approach one obtains more truthworthy measurements of the disposition of oriented molecules at surfaces than those obtained from absorption coefficients.