The photoluminescence (PL) and radioluminescence (RL) of Sn2+ centers in alkaline earthoxide (RO)-substituted ZnO-P2O5 glasses, which were prepared under Ar, were examined. Weconfirm that the network structure of the host glass was changed by the substitution of RO for ZnO.Although it seems that the optical absorption is independent of the kind of substituted RO, the PLintensities and the PL decay constants suggest that the local coordination state of the Sn2+ centeris affected by the substitution. From the results of RO-substituted SnO-ZnO-P2O5 (SZP) glasses,it is expected that an aggregation of Sn2+ centers occurs preferentially in a more highly substitutedsystem. The thermally stimulated luminescence of the RO-substituted glasses suggests thatstructural rearrangement during the quenching process induces both aggregation of Sn2+ centers anddecrease in the number density of traps in the SZP glasses.