The experiment examined the effects of the "point system" on the acquisition of vocabulary in a special class of mentally retarded children. It was found that conditions which provided for maximum reinforcement were more effective than conditions providing either minimum reinforcement or nonreinforcement. It was observed that the "point system" has contrib-uted greatly to the atmosphere of classroom situation. It was also observed that the teachers acting as experimenter tended to be freed from students' disruptive behavior, and that the student became highly motivated.