Objective: This study investigates the effectiveness of Token economy reinforcer on the academic achievement of 9th grade boy students with intellectual disability in science class in Tehran Province.

Materials & Methods: The experimental method by pre-test, post- test with the control group was used in this study. Twenty 9^th grade boy students with Intellectual disability from two junior high school were participated in this study. The sample was chosen by cluster method. After random assignment of students in both experiment and control groups, for students of experimental groups were used Token economy reinforce in the 17 sessions instruction and the control group students did not provide a reinforcer in the same sessions. The Wechsler intelligence test was used for matching the groups in terms of IQ and also a teacher made tests were used for measuring the progress of students in science. The data was analyzed by using descriptive statistics (mean, standard deviation, frequency charts and tables) and t-test.

Results: The results of this study showed that there was a significant increase in academic achievement of students with intellectual disabilities in the experimental group (used token economy) compare with the control group (P<0.001).

Conclusion: Token economy reinforcement increases the academic achievement of students with intellectual disability in science. Token economy reinforcers, increases motivation in students' intellectual disability.