There have been several reports of spin-selective carrier transport through organic films, along with some controversy about the mechanism. Using organic semiconductor films with well controlled purities and thicknesses and a combination of surface analytical and scattering techniques, we find that the interfacial morphology is a determining factor in the behavior of such devices. These findings will enable a more rigorous evaluation of the ultimate applicability of such devices for magnetic detection and spin-based logic. This project is a collaboration with the research group of Professor Daniel Reich of the Department of Physics, and is funded by the NSF MRSEC program. An additional outreach program is being carried out in collaboration with SRI International.