en خانواده و گروه درماني Family and group therapy پژوهشي Original Research Article <div style="text-align: justify;"><strong>Objective</strong>: Sexual behaviour is one of the most important developmental experiences in adolescence and may lead to longterm consequences. This study aimed to compare the effectiveness of cognitive-behavioural therapy (CBT), parent-child interaction therapy (PCIT), and their combination on depression, family functioning, and parenting stress in adolescents with problematic sexual behaviours (PSBs).<br> <strong>Methods</strong>: The sample consisted of 35 female students (10-13 years old) with PSBs from schools in Guilan Province, Iran, during the 2023-2024 academic year. They were identified by purposive sampling and based on the Sexual Behaviour Checklist and a clinical interview and were randomly assigned (using a table of random numbers) to three experimental groups (two groups with 12 participants and one group with 11 participants). To measure the variables, Maria Kovacs children&rsquo;s depression questionnaire, family functioning questionnaire, and parenting stress scale were used. after completing the questionnaires, the treatment sessions began. The pre-test, post-test design with three test groups was used, and data analysis was conducted using analysis of covariance (ANCOVA) with SPSS software, version 27.<br> <strong>Results</strong>: A statistically significant difference was observed among the experimental groups for depression (F=4.83, df=2, P=0.01, observed power [OP]=0.78) and family functioning (F=18.14, df=2, P=0.001, OP=1.00). However, no significant difference was observed among experimental groups for parenting stress (F=2.76, df=2, P=0.08).<br> <strong>Conclusion</strong>: According to the results, CBT-PCIT is more effective than CBT in reducing depression, and PCIT and CBT-PCIT are more effective than CBT for improving family functioning.</div> Parent-child interaction therapy (PCIT), Cognitive-behavioural therapy (CBT), Depression, Family function, Parenting stress, Problematic sexual behaviour (PSBs) 151 166 http://jpcp.uswr.ac.ir/browse.php?a_code=A-10-1028-3&slc_lang=en&sid=1 Fatemeh Mehrvarz taramehrvarz@webmail.guilan.ac.ir 0000-0002-2718-4183 No Faculty of Literature and Humanities, University of Guilan, Rasht, Iran. Abbas Abolghasemi abolghasemi1344@guilan.ac.ir 0000-0002-7378-9730 Yes Faculty of Literature and Humanities, University of Guilan, Rasht, Iran. Mahnaz Khosrojavid khosrojavid@guilan.ac.ir 0000-0002-4079-9094 No Faculty of Literature and Humanities, University of Guilan, Rasht, Iran. Abbas Ali Hosseinkhanzadeh khanzadehabbas@guilan.ac.ir 0000-0003-4060-0011 No Faculty of Literature and Humanities, University of Guilan, Rasht, Iran.