The purpose of this study was to compare the effectiveness of group and individual positive psychotherapy on the cognitive and physical dimensions of orphaned or neglected female adolescents (those in foster care or with dysfunctional guardians) suffering from Persistent Depressive Disorder (PDD). The research employed a quasi-experimental design featuring a pre-test, post-test, and a one-month follow-up. The statistical population consisted of all female adolescents aged 13–17 in foster care in Bonab, East Azerbaijan, in 2020. A sample of 45 participants was selected and randomly assigned to a control group (n=15), an individual experimental group (n=15), and a group intervention experimental group (n=15). The experimental groups received six 90-minute sessions of positive intervention, while the control group received no intervention. Participants completed the Beck Depression Inventory (BDI) at pre-test, post-test, and follow-up stages. The results indicated a significant difference between the means of the individual and group positive intervention groups regarding the cognitive symptoms of persistent depression (P = 0.000). Based on the calculated marginal means, the individual positive therapy group (Mean = 5.222) scored lower than the group therapy group (Mean = 7.067), indicating that individual intervention is more effective than group intervention in improving cognitive symptoms. However, the difference between the two intervention groups regarding physical (somatic) symptoms was not significant (P = 0.033). Consequently, the findings suggest that individual positive psychotherapy may yield greater efficacy in reducing and managing the symptoms of persistent depression.