The purpose of the present study was to investigate the acquisition, maintenance, and generalization effects of antecedent prompt and testing procedure (APTP) on teaching emergency phone numbers to youth with developmental disabilities. Three youths with mental retardation participated in the study. All participants were inclusion students at a regular school. A multiple probe design across behaviors with probe conditions was used in the study. Maintenance (i.e., one and three weeks after the termination of the intervention) and generalization across trainers probe sessions were conducted. Parents' opinions regarding teaching emergency phone numbers to their children were also included in the study. The findings showed that APTP was effective teaching emergency phone numbers to youths with mental retardation at acquisition, maintenance, and generalization levels. Furthermore, the social validity results of the study were very positive in general. (Contains 1 table and 3 figures.)