We evaluated the effectiveness of group safety training and in situ feedback and response interruption to teach preschool children to avoid consuming potentially hazardous substances. Three children ingested ambiguous substances during a baited baseline assessment condition and continued to ingest these substances following group safety training. In situ feedback and response interruption resulted in a decrease in opening ambiguous containers; this decrease was maintained when ambiguous novel containers were presented and when assessments occurred in a novel setting and with a novel experimenter. For 2 children, these gains were also maintained during a brief follow-up period. Twelve children did not ingest ambiguous substances prior to training, and group safety training did not evoke inappropriate ingestion. (Contains 1 figure.)