We measured the homogeneous width of the 6 D 7 2 to 8 S 7 2 transition of trivalent curium in a fluorophosphate and a fluorozirconate glass as a function of temperature from 15 to 100 K by resonant fluorescence line narrowing (FLN). The line width varies as T 2 over the entire temperature range, and is an order of magnitude larger than homogeneous widths observed for trivalent lanthanide ions in fluoride glasses. Estimates of the ground-state splitting are also possible from the FLN spectra. We present a simple model that puts limits on the range of splittings possible in the glass and compare them to splittings measured in crystals.