Experimental studies of the diamond (111) surface are presented. While no intrinsic surface states have been found on the 1×1 surface, our new results in ultraviolet photoemission spectroscopy (15 eV?hν?25 eV) show evidence of a band of surface states on the 2×2/2×1 reconstructed surface. The band of surface states (with an integrated emission on the order of one filled state per surface atom) is centered at 2.5 eV below the Fermi level (1.1 eV below the valence-band maximum). The band width is 1.8 eV FWHM. In the case of the 2×2/2×1 surface structure, the downwards band-bending is greater by 0.75 eV and the electron affinity is greater by 1.4 eV over the respective values for the 1×1 surface. These new studies necessitate a quantitative revision of our band-bending model [J. Vac. Sci. Technol. 17, 1087 (1980)], although no change in basic concept is required. Preliminary photon-stimulated desorption (PSD) results over the photon energy range hν = 18–35 eV find hydrogen on the 1×1 surface. This surface hydrogen (possible in the form of hydroxide) may explain the absence of surface states on the diamond (111) 1×1 surface.