RESUMEN
Adolescence is a sensitive period and psychological health during this period is of significant importance. Several studies suggest that self-esteem is a better predictor of success in studying than intelligence scores. Having assertiveness is considered important in having a high self-esteem. This study has been carried out in order to determine the influence of assertiveness training on self-esteem in high-school female students. In this semi-experimental study, two female schools with 751 students were selected randomly from one of the four education regions of Shiraz, Iran. All of the students were evaluated using Coopersmith Self-Esteem Inventory [CSEI] and Gambrill-Richey Assertion Inventory [GRAI]. Students who had a test score of less than 25.4 were identified students with low selfesteem. Among whom, those who possessed low assertiveness means, their test scores were less than 44, were also characterized. Finally, 60 students were selected and allocated to intervention and control groups. No training was conducted for the control group, but the case group undertook assertiveness training for a period of 4 weeks, 2 times a week for 90 minutes. The Coopersmith selfesteem and Gambrill-Richey Assertion Inventories were repeated after finishing 8 sessions. These tests were also repeated after 2 weeks to evaluate the rate of training continuity. T-test did not show a significant statistical difference between the mean and standard deviation of the scores of self-esteem and assertiveness before training among research samples between case and control groups [P = 0.30]. The mean scores of self-esteem and assertiveness of the experimental group had significant differences immediately [34.1 and 92.8, respectively] and after 2 weeks of training [32.2 and 93, respectively] comparing with before training and with control group [respectively, P = 0.035, P = 0.045]. Assertiveness of the control group did not show any significant statistical difference during the aforesaid three times [P > 0.05]. The obtained results indicate an increase in the rate of self-esteem and assertiveness after a period of assertiveness training among the case group. Actually, assertiveness training is significantly effective on the rate of assertiveness and self-esteem of students. In addition, results show that the influence of assertiveness training does not last for a short duration but its effect has remained as such after 2 weeks of training