Background and purpose: The theoretical foundations of hope therapy have rarely been used to improve the psychological symptoms among adolescent girls, and there are few data available about the effectiveness of group hope therapy. Present study aimed to investigate the efficacy of group hope therapy on the treatment of depression, loneliness, and self-efficacy in girl students.

Method: The present research was experimental study with pretest-posttest design and control group. The study population consisted of all tenth and eleventh grade female students who were studying in the district one schools of Rasht in 2014-2015 academic year. 200 female students were selected using random cluster sampling method and filled out Beck depression inventory ‌ (1971), Asher loneliness (1983), and Sherer and Adams self-efficacy scale (1985) as their pretest. After scoring and screening the questionnaires, 30 students with the lowest scores were selected and randomly assigned to experimental (n =15) or control groups (n =15). The control group received no intervention, while the experimental group received an eight-session (90 min/ per session) group hope therapy.

Results: the results of univariate analysis of covariance showed that comparing to control group, experimental group scored significantly lower on depressed mood and loneliness (p < .05). However, the groups did not differ significantly in terms of self-efficacy (p > .05).

Conclusion:  Group hope therapy is an effective way to decrease depression and loneliness in female high school students. Based on these results, it is suggested that educational counselors use group hope therapy in working with students with mood disorder or loneliness.