Objective: The present study investigates the development of social information processing (SIP) in students with mild intellectual disabilities with regard to the social information processing model presented by Crick and Dodge (1994).  Method: The sample consisted of 120 students ageing 10 to 12, 13 to 15 and 16 to 18 years. They were selected from the exceptional schools in Shiraz and were interviewed individually using Tur-Kaspa and Bryan (1994) social stories. Results: The results indicated the presence of a significant difference between the mean scores of the first and the third group of students in all stages of SIP. However no significant difference was observed between the mean scores of the second group and the other two groups in any of the SIP steps. Conclusion: This study concludes that there probably exists a slow social cognition development in these students.