Aims: People’s social behavior mainly depends on their moral reasoning level. Therefore, approaches which affect promotion of moral reasoning may provide the society with better social behavior.

Methods: This is a quasi-experimental research in pre-test and post-test design accompanied by a control group who were randomly assigned. Statistical population were adolescent students of Isfahan in the academic year of 92-93, of whom experimental group and control group were chosen through cluster random sampling.

Results: Statistical analysis shows that in pre-observation, the average score of moral reasoning for experimental group (1.33) was lower level than control group’s average (1.45). After the drama therapy, the experimental group’s average score of moral reasoning (2.44) increased in comparison to the control group (1.54). In fact, the difference between two groups was significant.

Conclusion: Results show that the experimental group has illustrated a considerable increase in moral reasoning. Actually, statistic results emphasized that drama therapy could improve the moral reasoning.