The answer to the question in the title of this paper (Can luminescence spectroscopy contribute to the elucidation of surface species?) is simple: in specific cases yes, but in general no. The examples described above, viz. the trivalent rare earth ions on silica (PVG) and the vanadate group on silica, illustrate that luminescence spectroscopy, especially at low temperatures, can contribute to the elucidation of surface species. In both cases a clear model can be derived from the spectral data obtained; this model is confirmed by data obtained by the application of other techniques. On the other hand, the examples of Gd3+ on and in zeolite A and of other transition-metal oxo groups on silica make it clear that luminescence spectroscopy is not a generally successful technique for surface studies. If a variety of luminescent species are present, or if the spectra show broad, structureless bands it is very difficult to arrive at reliable conclusions. In our opinion the literature contains examples where such conclusions are nevertheless drawn, but they can be questioned. Here we have of course abandoned a very trivial objection against luminescence spectroscopy, viz. that nonluminescent species are missed anyhow.