We exploit the upconversion process, utilizing it as a sensitive tool in site-selective spectroscopy of rare earth ion-doped solids. In the Y3Al5O12:Pr3+ praseodymium-doped yttrium aluminum garnet (YAG:Pr) crystals the Pr ions are situated in sites having slightly different environments. Under pulsed excitation into the D-1(2) level, the upconverted emission from the P-3(0) level of each Pr subsystem exhibits its unique, and easily identifiable, response to pulsed excitation, simplifying the process of selectively exciting ions in different sites. Using this technique, we have been able to identify three different sites in a sample of YAG with Pr concentration of 0.5%. We present the physical reasons for the sensitivity of this technique as an example of a useful approach to distinguish among atomic systems residing in slightly dissimilar environments. (c) 2007 American Institute of Physics.