Background and Aim: Teenage girls who have experienced parental divorce have a pressing need to overcome post-divorce problems, and trauma-focused cognitive behavioral therapy is one of the interventions that can help individuals in this regard. The present study was conducted to determine the effectiveness of trauma-focused cognitive-behavioral therapy on loneliness and communication skills among adolescent girls experiencing grief related to parental divorce. Research Method: The statistical population of this study included all divorced teenage girls living in Yazd who referred to counseling clinics and psychological services in this city in 2024-2025, from which 30 teenage girls were selected through purposive sampling and randomly assigned to an experimental group (15 girls) and a control group (15 girls). The measurement tools were Russell et al.'s (1996) loneliness questionnaire and Jerabek (2004) communication skills questionnaire. The experimental group received trauma-focused cognitive behavioral intervention for 12 sessions, one session per week for 90 minutes. Data were analyzed using SPSS-26 and univariate analysis of covariance. Findings: The results showed that, after controlling for the pretest effect, there was a significant difference between the mean posttest scores of loneliness (p<0.05) and communication skills (p<0.05) in the experimental and control groups. Conclusion: trauma-focused cognitive behavioral therapy can be used as an effective treatment method to reduce loneliness and increase communication skills in adolescent girls who have experienced parental divorce.