Violence is a major social challenge that has predominantly been examined within the framework of male dominance over women, while intra-gender violence has received far less scholarly attention. Among these, violence of women against women represents a relatively hidden and understudied phenomenon with significant implications, as it contributes to the reproduction of discriminatory attitudes and undermines female solidarity. The present study aims to explain the cultural factors influencing physical and verbal violence of women against women in municipal districts 1, 2, 16, and 17 of Tehran. This research adopts a qualitative approach using grounded theory methodology based on Strauss and Corbin (1998). Data were collected through semi-structured interviews with 20 victimized women. The selection of this method was due to the complex and multi-layered nature of the phenomenon and the lack of sufficient theoretical development in this field in Iran. Data analysis was conducted through open, axial, and selective coding. The findings reveal that a set of cultural factors-including internalized misogyny, gender socialization, negative competition, conflict of interests, and conformity with patriarchal norms—play a significant role in shaping violence among women. These forms of violence are primarily expressed through humiliation, sarcasm, rumor-spreading, and social exclusion, and in some cases escalate into physical aggression. The results indicate that violence of women against women is not merely an individual behavior but a reflection of broader socio-cultural structures reproduced through socialization processes. Therefore, transforming cultural attitudes, promoting conflict resolution skills, and strengthening female solidarity are essential measures for mitigating this phenomenon.