The thickness-dependent interfacial band structure was determined for thin films of C-60 on Ag(111) by angle-resolved two-photon photoemission spectroscopy. Dispersions of molecular-orbital derived bands ( HOMO, LUMO+1, and LUMO+2) were acquired, and limits were placed on their possible effective masses. A group theoretic approach is also incorporated to further understand the properties of these states. The HOMO, LUMO+1, and LUMO+2 bands possess ( best-fit) effective masses of - 7 m(e), - 7 m(e), and - 12 m(e), respectively. These values are consistent with theoretical calculations, averaged over the closely spaced subbands for each state, and provide practical limits on the effective fundamental charge-transport properties of C-60 films.