Disparities exist in the availability of high-quality early childhood education and care settings (ECEC) across communities within the United States. Teachers have an imperative role in fostering children’s socioemotional development; however, when the classroom climate deteriorates due to disruptive behavior, meeting these emotional and learning needs becomes more difficult. Dealing with challenging behaviors can lead to emotional exhaustion which is directly linked to a decrease in teacher sense of efficacy. Teacher–Child Interaction Training-Universal (TCIT-U) targets teachers’ skills to provide quality interactions and decrease child behavior problems. Despite evidence that teacher sense of self-efficacy can inhibit negative teaching practices, a lack of research has explored this construct as related to TCIT-U. The current study is a randomized, wait-list control study measuring the change of teachers’ sense of self-efficacy after participating in TCIT-U, and the first known of its kind. The study included mostly Hispanic (96.4%) teachers (N = 84) of ECEC programs across 13 unique sites serving 900 children ages 2–5 years from low-income, urban areas. Results from inferential statistics and hierarchical linear regression tests demonstrated TCIT-U as an effective intervention to improve teachers’ sense of efficacy in classroom management, instructional strategies, and student engagement. In addition, this study contributes to the effectiveness of TCIT-U as an in-service training which targets teacher communication skills for teachers with diverse backgrounds in ECEC settings with mostly dual language learners.