Background: Children's early classroom experiences, particularly their interpersonal interactions with teachers, have implications for their academic achievement and classroom behavior. Teacher-child relationships and classroom interactions are both important aspects of children's early classroom experiences, but they are not typically considered together in studies of early childhood classrooms. The bioecological model suggests that both uniquely impact children's development. Objective: The objective of this study was to examine the joint impact of individual teacher-child relationships reported by the teacher and observed classroom interactions to identify associations between these and children's outcomes. Methods: Using the Early Childhood Longitudinal Study-Birth cohort, multiple regression was employed to test the hypothesis that teacher-child relationships and classroom interactions are uniquely related to children's classroom behavior and academic achievement. Further, a moderation model was tested to examine the moderating impact of teacher-child relationships on the association between classroom interactions and children's outcomes. Results: Teacher-child relationships were related to children's concurrent academic achievement and classroom behavior, and to children's classroom behavior assessed one year later. No main effects of classroom interactions were identified; however, teacher-child relationships moderated the associations between classroom interactions and children's preschool classroom behavior. Conclusions: Findings suggest that teacher-child relationships are important for children's development in classrooms, even after accounting for classroom interactions. Professional development for teachers and measurement in classroom research should address teacher-child relationships in addition to classroom interactions.