The present study aimed to examine the goodness-of-fit of a model of narcissistic tendencies based on childhood trauma and the quality of interpersonal relationships, with the mediating role of inferiority feelings. This research is fundamental in terms of its objective and employs structural equation modeling as its methodology. A total of 200 high school students from Kuhdasht County (a city in Iran) were selected using convenience sampling during the 2024–2025 academic year. Data collection was conducted using the Childhood Trauma Questionnaire (CTQ), the Quality of Relationships Inventory (QRI), the Comparative Feelings of Inferiority Index (CFII), and the Narcissistic Personality Inventory (NPI). Data analysis was performed using structural equation modeling with the Partial Least Squares (PLS-SEM) approach. The results indicated that the proposed model demonstrated a good fit. However, the mediating role of inferiority feelings in the relationship between childhood trauma and the quality of interpersonal relationships with narcissistic tendencies was not confirmed (P > 0.05). The findings suggest that childhood trauma and the quality of interpersonal relationships have direct effects on narcissistic tendencies. However, it appears that variables other than inferiority feelings may mediate these relationships.