The assignments of bands in the electronic spectra of Y2O3:Er3+ to Er3+ ions situated at S-6 symmetry sites (Silver, J.; Martinez-Rubio, M. I.; Ireland, T. G.; Withnall, R. J. Phys. Chem. B 2001, 105, 7200; Silver, J.; Martinez-Rubio, M. L; Ireland, T. G.; Fern, G. R.; Withnall, R. J. Phys. Chem. B 2001, 105, 948) are shown to be incorrect, and some of the conceptual errors in these works are also corrected. For example, the emission bands assigned to 2H(11/2) --> I-4(15/2) transitions at S-6 sites are reassigned to P-2(3/2) --> I-4(11/2) transitions of Er3+ at C-2 sites. In fact, all of the visible and ultraviolet bands can be assigned to Er3+ ions situated at C-2 sites. The optical spectra are remarkably complete and uncluttered from vibronic structure, except for emission transitions to the two highest ground-state crystal field levels, where the multiple structures are assigned to electron-phonon coupling effects.