Peer-mediated social initiations and prompting/reinforcement procedures were evaluated (in training and generalization sessions) as interventions for increasing the positive social behavior of four autistic children. During baseline, the peer trainer made few social initiations and did not prompt or socially reinforce subjects. For two subjects, baseline was followed by social initiation intervention, and for the other two, baseline was followed by prompting and social reinforcement. Both interventions produced dramatic and comparable increases in positive social behavior in training sessions. Post-treatment responding was not observed for either intervention. When interventions terminated in a second baseline period, the subjects' behavior returned to the level observed during the initial baseline. The subjects were then exposed to the intervention procedure they had not yet experienced. Again, there were positive and comparable behavior changes in the treatment setting, but no increase in positive social behavior was observed during generalization assessment.