In this study, positive social initiations by an age-peer was evaluated as an intervention for isolate preschool children in training and generalization sessions. During baseline, the confederate made few social approaches to the target subjects. The confederate greatly increased his rate of positive social initiations during the first intervention, decreased social approaches during a second baseline, and increased social approaches again in a second intervention phase. Increases in confederate initiations resulted in an immediate acceleration in the frequency of subjects' positive social behavior during training sessions. Additionally, for two of the three subjects, positive social behaviors were also observed to increase during generalization sessions. The results suggest that (a) peers may be trained successfully to set the occasion for positive social behaviors by withdrawn classmates, (b) increased social responding by withdrawn children in the presence of frequent peer social initiations may also generalize beyond the training setting, and (c) the magnitude of direct and generalization effects appears to be related to the entry-level repertoire of target children.