Site-selective fluorescence and laser excitation spectroscopy for different types of optical centers in SrF2 : Nd3+ (0.3 - 1.0%) and SrF2 : La3+ (1.0%) : Nd3+ (0.2%) were performed at 4.2 K. The crystal-field levels of the 4I9/2, 4F3/2 , and 4G5/2 multiplets for different Nd3+ optical centers were determined in SrF2 : Nd3+ (0.3%). An attempt was made to identify some of the new optical centers on the basis of their fluorescence lifetimes and crystal-field splitting. Some models of these centers have been discussed. Two-six times reduction of the 4P3/2 multiplet lifetime was observed in the pair M-center in comparison with the single optical centers due to energy cross-relaxation in the pair. A fine splitting of the levels at the 4I9/2(1) → 4G5/2(1) crystal-field transition (1.5 cm-1) similar to that in CaF2 (2.4 cm-1) was found for the Nd-Nd pair in SrF2. The variation of the splitting from CaF2 to SrF2 nicely demonstrates the R-5 dependence of coherent quadrupole-quadrupole interaction. © 1999 Elsevier Science B.V. All rights reserved.