The absorption, excitation, and fluorescence spectra and lifetimes of Mn2+and Nd3+in RbMnF3were investigated in the 5 to 300°K region. The fluorescence of Mn2+in these systems was found to originate from two metastable levels centered at 5820 and 6300 Å. The Nd3+emission appears as two groups of sharp lines centered atsim10 600and ∼8900 Å. Energy transfer from manganese to neodymium is observed even at room temperature where the Mn2+fluorescence is completely quenched and the energy transfer mechanism was found to be of nonradiative type. Detailed information was obtained on the temperature dependence of the fluorescence intensities and decay times of the manganese and neodymium emissions. The results give information on the kinetics of these fluorescent systems.