We studied the luminescence properties of Eu2+ in CaAl2Si2O8. In CaAl2Si2O8:Eu2+ phosphor, two emission bands were observed. Because the two emission bands of CaAl2Si2O8:Eu2+ phosphor are quite different, it can be presumed that Eu2+ ions occupy two types of sites, namely, Eu-1 and Eu-2. The energy transfer between the Eu2+ ions are elucidated from the critical concentration quenching data based on the electric multipolar interaction of the Eu-1 and Eu-2 sites, respectively. In addition, the dominant multipolar interaction character of the Eu-2-site emission center was investigated from the relationship between the emission intensity per activator concentration and the activator concentration. (C) 2004 The Electrochemical Society.