This longitudinal study evaluated the impact of dyadic and classroom-level teacher-child relationship quality in first grade on children's psychosocial and academic adjustment in first (N = 3,784), second (N = 3,666), and third (N = 3,582) grade, controlling for several child features, namely, child demographics and children's initial levels of adjustment in kindergarten. Results of multilevel hierarchical regression analyses showed that first-grade dyadic relationship variables (i.e., teacher-child conflict and closeness) as well as classroom relational climate variables (i.e., the average level of teacher-child conflict and closeness in the classroom) were associated with children's psychosocial adjustment in the first years of primary school. Associations between first-grade dyadic relationship quality and classroom relational climate, on the one hand, and academic achievement on the other, however, were negligible. (Contains 4 notes, 6 tables, and 3 figures.)