The luminescence of Sr1-xPbxTiO3 powder samples is reported for several values of x. In all cases, except x = 1, the self-trapped exciton (STE) emission of SrTiO3 is accompanied by an overlapping emission band at lower energy due to a center involving Pb2+. The relative emission intensities of these individual bands vary with temperature and Pb2+ concentration. The bandgap energy is decreased in the samples doped with 50% and 100% Pb2+, which is explained by the increased Pb2+ wave-function overlap. It is concluded that the luminescence due to Pb2+ centers involves decay from conduction band levels to the ground level of Pb2+. This level appears to be situated just above the valence band. A broad-band luminescence of the same origin is found in PbTiO3. In addition, evidence for free exciton emission is observed.