Background and Purpose: Children's behavioral problems can lead to frequent problems in school and not only endanger the education of children, but also cause social problems and reducing their attention and self-esteem. The purpose of the research was to the effectiveness of cognitive therapy based on mindfulness on children's behavioral problems.
Method: The research method was semi-experimental with pre-test-posttest design with control group. The statistical population consisted of all sixth grade students in the 2nd district of Tehran in the academic year of 1395-1959, among them 20 students were selected using purposeful sampling method and placed in the experimental and control groups. The research tools were child and adolescent mindfulness measure (Greco and Baer, 2011) and behavior problems checklist (Quay-Peterson, 1987). Before intervention both groups were evaluated. Cognitive therapy based on mindfulness was trained in 12 sessions of 90 minutes to the experimental group. Covariance analysis was used to analyze the data.
Results: The findings showed that the students in the experimental group had significantly lower behavioral problems (symptoms of conduct disorder, attention problems and immaturity, anxiety and withdrawal symptoms) in the post-test stage. Also, there was a significant increase in mindfulness and acceptance of children participating in the program (P <0.01).
 Conclusion: According to the findings of this study, cognitive therapy based on mindfulness for children can be used to reduce behavioral problems and increase their mental awareness.