Introduction: It is believed that children with mild to borderline intellectual functioning are not successful in processing the information received from peers and other people in their surroundings during social interactions, which leads to challenging and aggressive behavior. The purpose of this study was to investigate the effect of social information processing (SIP) model intervention on reducing challenging behavior among children with mild to borderline intellectual functioning. Method: For the purpose of this study, a two-way repeated measures ANOVA, with pre-post -- and follow up test in two groups were employed. A total of 40 children in the age of 5-10 participated. Participants were 33 boys and 7 girls with a mean age of 8.32 (SD=3.14) and a mean IQ of 75.64 (SD=7.34). Results: Findings from this study revealed the effectiveness of social information processing (SIP) model intervention on reducing challenging behavior among children with mild to borderline intellectual functioning. Discussion and Conclusion: In conclusion, results from this study suggested that children with mild to borderline intellectual functioning utilized the Social Information Processing (SIP) Model and their challenging behaviors and prosocial behaviors (challenging behavior) could be reduced. Application and implications, limitations, future research were included.