Pentacene, perylene, and sexithiophene are all materials being used in organic thin film transistors due to their relatively large mobilities. It has been suggested that the functional behavior in organic thin film transistors occurs within the first few molecular layers of the device at the interfaces between the organic and the metals and dielectrics used in fabrication of the thin film transistors. This makes understanding the electronic behavior of the interfaces involved in these devices critical. In order to better understand these interfaces we investigated the interface formation of pentacene, perylene, and sexithiophene on conductors and dielectrics using photoemission spectroscopy to examine layer by layer organic growth onto these materials. We observed indications of dipole formation at the interfaces between the metals and organics for organic on metal deposition, ranging from a 1eV dipole at the interface between sexithiophene and gold to a -0.46eV dipole at the interface between pentacene and calcium. There appears to be a linear relation between the interface dipole and metal workfunction. On the other hand, for metal on organic deposition, more complex material intermixing takes place and as a result, the electronic structure of the interface differs from that of organic on metal deposition. Possible charge transfer, dipole formation and energy level bending at these interfaces will be discussed.