Background: Improving childcare quality is an important goal in South Korea as many infants attend childcare centers. The quality of teacher-child interactions is a common and crucial predictor of childcare quality. Thus, it is imperative to identify the relative contributions of the variables associated with improving the interaction quality of childcare providers. Objective: This study explored predictors of interaction quality among childcare providers. This study hypothesized that multiple variables in each domain impact the interaction quality of childcare providers. These variables include childcare providers' background, psychological well-being, classroom characteristics, and work environment. Methods: Survey data were collected from 803 childcare providers who were responsible for classes comprising children aged 0 to 2 years. A factor analysis of the dependent variable, correlation, and hierarchical regression were performed in this study. Results: Among the predictors of each domain that influence interaction quality, the "happiness" of childcare providers included in the psychological well-being domain emerged as the strongest variable. Subsequently, the variables "belief," "expectation," "value," "distress and loneliness," "teacher-director relationship," and "children's age" in the professional work environment domain followed. Conclusion: Future studies and interventions should explore diverse ways to mitigate the negative emotions experienced by childcare providers. Furthermore, ongoing professional development should be emphasized as a cost-effective way to improve interaction quality.