Background: Research in Western countries has shown the contribution of early teacher--child relationships and classroom emotional support on children's behavioral adjustment in pre-schools. Results with regard to the direction and strengths of the relationships seem inconclusive, moreover, such research is lacking in African countries. Objective: To examine the change and predictability of children's behavioral adjustment in Tanzanian pre-primary schools. Method: Longitudinal data were collected twice over a 1-year interval. Twenty teachers and their 310 children from 20 schools in the Ilala district, Dar es Salaam region, participated in the study. Methods used for data collection were teacher questionnaires and classroom observation. Results: Results showed that over time, children's aggressive behavior and teacher--child conflict decreased, whereas teacher-child closeness increased. Prosocial and anxious behavior remained stable. Multilevel and longitudinal analyses indicated that teacher-child closeness and conflict predicted children's aggressive behavior. Children's prosocial and anxious behavior predicted teacher-child closeness, while their prosocial, aggressive and anxious behavior at the individual level and anxious behavior at the aggregated class level predicted teacher-child conflict. Conclusions: Teacher-child relationships and children's behavior relate in a bidirectional way. If the relationship between a teacher and a child is characterized by conflict, children are more likely to develop difficult behavior and teachers find it more difficult to manage the children. These results imply that pre-primary teachers need to be trained on how to identify signs of behavioral problems in children and to establish an emotional supportive classroom environment and teacher--child closeness for a positive school trajectory in children.