Background: The present study was aimed at developing a grounded theory on how bibliotherapy influences children with intellectual disabilities. Method: Participants were selected among the students of four primary schools in Tehran. They received, for 3 years, a special bibliotherapy intervention provided by the public library in cooperation with a team of experts; The bibliotherapy sessions were held once a week during the academic year. 10 teachers, 4 mothers, and 4 agents (librarians) were selected using a purposeful sampling method, and were interviewed using in-depth interviews. Result: Data analysis was performed using the grounded theory. 'Improvement of skills necessary for adjustment to disability' was identified at the core of grounded theory. Conclusion: Bibliotherapy, as a guided learning method and an add-on therapy, based on an accurate identification of intellectually disabled children's needs and behaviors, providing them with supplemental education materials, empathy, and cooperation among experts from different fields.