We compare optical homogeneous linewidth measurements for the resonant5D0−7F0transition of Eu3+in glasses and crystals. The linewidth in the amorphous hosts is significantly larger than in crystals with similar coordination, and shows an unusual temperature dependence which cannot be explained by the normal ion‐phonon relaxation mechanisms. This behavior probably arises from an interaction between the impurity ion and low energy ’’disorder modes’’ in the glasses. Possible models are discussed, consistent with recent NMR and ultrasonic attenuation experiments. In addition, excitation scans have been taken in search of discrete sites for the rare earth impurity in the glassy host. No such sites can be detected with a 1GHz resolution.