Emotion understanding and emotion regulation play important roles in children's development, but we have only a limited understanding of how these constructs are socialized. Constructionist theories suggest that as children engage in interactions with caregivers, they learn to associate words naming emotion categories with conceptual representations of specific emotions, leading to greater emotion understanding. In this preregistered study, we posit emotion word knowledge as a key feature of emotion understanding. Using path analysis with a cross-sectional sample of 252 mainly low socioeconomic status children (aged 4-8 years) and their caregivers collected between 2018 and 2024, we examined indirect effects of implicit parental emotion socialization (difficulties with emotion regulation and emotional expressivity) on children's emotion regulation through children's emotion word knowledge. While parental difficulties with emotion regulation and expressivity were unrelated to children's emotion word knowledge, child emotion word knowledge predicted parent reports of children's adaptive emotion regulation. In addition, we observed an indirect effect of children's verbal intelligence on adaptive emotion regulation through children's emotion word knowledge. In contrast, we observed a direct effect of parental difficulties with emotion regulation on children's dysregulation. These findings align with constructionist theories underscoring the importance of emotion word knowledge for the development of emotion regulation skills and begin to shine light on how family contexts might support children's development of emotion word knowledge. (PsycInfo Database Record (c) 2025 APA, all rights reserved).