The energy-level scheme of Gd+3 in CaF2 is investigated using thermoluminescent techniques. A large number of emission lines is found in the thermoluminencence spectrum. This large number of lines is attributed to different site spectra. The effect on the emission spectra of heat treatment and different origins of crystals is shown. The differences in spectra between samples result from the variations in abundance of the various rare-earth ion sites. This abundance is primarily determined by growth conditions and impurity concentrations.