Relatively few studies have focused on relational factors within the school environment that could moderate the associations between temperament and behavior problems. The purpose of this longitudinal study was to examine whether student-teacher relationship quality (i.e., Closeness, Conflict, and Dependency) moderated longitudinal associations between child temperament (i.e., Negative Affectivity, Surgency/Extraversion, and Effortful Control) and externalizing and internalizing problems. The participants were 744 elementary school students (mean age 8.4 years at study entry) followed over 3 years (four measurement times). Parents assessed their child's temperament at study entry (T1) and the children reported their self-perceptions of problems 3 years later (T4). Student-teacher relationship quality was constructed as a latent variable based on ratings from three different teachers over 3 years (T1, T2, T3). Latent moderated structural equations revealed that a low level of Surgency/Extraversion was associated with less internalizing problems but only for children experiencing a high level of Closeness with their teachers. A high level of Negative Affectivity was associated with more internalizing problems, but only for children experiencing a high level of Conflict or a high level of Dependency with their teachers. Student-teacher relationship quality did not moderate the associations between temperament and externalizing problems. Improving student-teacher relationship quality through focused interventions thus represents a useful strategy.