Objective: Difficulty in regulating emotions is a concept related to psychopathology that occurs not only in childhood but also in adulthood. This emotion develops in early childhood via the interaction of the child with the parents, especially the mother. The aim of this study is to examine the role of attachment styles and personality traits of the mother in the relationship between emotion regulation of the mother and her child. Methods: This study comprised of 280 mothers, 24-50 years (35.92±5.14), 148 girls (52.9%) and 129 boys (46.1%) in the age range of 3-6 years. Sociodemographic Data Form, Emotion Regulation Checklist (ERC), Difficulties in the Emotion Regulation Scale Brief Form, Basic Personality Traits Inventory and Relationship Scales Questionnaire were applied to the partici-pants. Results: Significant difference in sociodemographic variables was found in boy's favor in the ERC-negative subscale compared to child sex variables only. Positive correlations were found between the children's ERC-nega-tive subscale and maternal emotion regulation difficulties, indifferent and fearful affiliation neuroticism and negative valence personality traits; and negative correlations were found with extraversion and responsibility characteristics according to the Pearson's correlation analysis. According to the mediation analysis, neuroticism, negative valence and fearful attachment style of the mother had a partial mediating effect on the relationship between the emotion regulation of the child and the emotion regulation of the mother. Conclusion: In our study, it was observed that the difficulty of regulating emotion was related to the difficulty of regulating emotion of the mother rather than the ability of the child to regulate emotion and some personality traits were effective factors in the emotion regulation difficulty of the child. Investigating other family-related factors correlated with child emotion regulation difficulties will contri-bute to the understanding of emotion regulation process. [Anadolu Psikiyatri Derg 2020; 21(3.000): 311-318]