This study investigated the cross-lagged associations between teacher-student relationships and problem behaviors in a sample of 440 Finnish students (half of them identified as being at risk of reading difficulties). The degree to which these associations were moderated by a child's gender, academic performance, risk for reading difficulties, parental education, and having the same teacher over 2 years was examined. The teachers evaluated the students' problem behaviors and reported closeness and conflict with a particular student. The results showed that the higher the students scored on externalizing problems in Grade 4, the more conflict teachers reported 2 years later. Moderator analyses revealed that internalizing problems predicted higher levels of closeness for boys only. Conflict predicted internalizing problems among students who had the same teacher across the 2 years. The results emphasize the importance of investigating the transactional links in different subgroups.