Tehran University of Medical Sciences Iranian Journal of Psychiatry 1735-4587 0 0 2026 09 12 1 12 EN Hatef Tirgari Seraji Department of Psychology, Faculty of Educational Sciences and Psychology, University of Mohaghegh Ardabili, Ardabil, Iran. Amirhossein Rasouli Student Research Committee, Department of Clinical Psychology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Omid Saed Social Determinants of Health Research Center, Health and Metabolic Diseases Research Institute, Zanjan University of Medical Sciences, Zanjan, Iran AND Department of Clinical Psychology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran. Sana Bayazidi Department of Clinical Psychology, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran. 2026 03 10 2026 08 26 Objective: Depression represents a significant global health burden, with interpersonal problems and rumination emerging as crucial correlates. However, the precise nature of the associations linking these elements remains unclear. This study investigated the statistical mediation pattern of rumination in the relationship between interpersonal problems and depressive symptoms in the Iranian population. Method: A cross-sectional study was conducted with 564 participants (38.5% male, 61.5% female; mean age = 21.50, SD = 3.47) recruited through social media networks in Zanjan, Iran. Participants completed the Inventory of Interpersonal Problems (IIP-32), Rumination Response Scale (RRS), and Beck Depression Inventory-II (BDI-II). Structural equation modeling was employed to test the hypothesized mediation model. Results: The structural model demonstrated an excellent fit (χ²/df = 2.904, RMSEA = 0.055, CFI = 0.979). Interpersonal problems were significantly associated with both rumination (β = 0.637, P < 0.001) and depressive symptoms (β = 0.253, P < 0.001). Rumination showed a significant indirect association (β = 0.373, P < 0.001) in the relationship between interpersonal problems and depression symptoms. The total association of interpersonal problems with depressive symptoms was substantial (β = 0.627, P < 0.001). Conclusion: The findings confirm that interpersonal problems are both directly and indirectly associated with depressive symptoms, with the indirect statistical pathway operating via rumination. This suggests that the interplay between interpersonal difficulties and ruminative thinking patterns may be a relevant consideration for future clinical research aiming to improve depression outcomes. https://ijps.tums.ac.ir/index.php/ijps/article/view/4581 https://ijps.tums.ac.ir/index.php/ijps/article/download/4581/1355