The aim of this research was to examine the mediating role of teacher–pupil interaction in the relationship of temperament to self-esteem and school success among year-7 and year-8 elementary-school pupils in Croatia and Bosnia & Herzegovina (B&H). The assumptions on the contribution of the dimensions of temperament (self-control and negative affectivity) and teacher–pupil interaction (influence and proximity) in explaining pupils' self-esteem and school success were partially confirmed. Similar relationships among the measured variables were confirmed in both samples of pupils. Self-control, negative affectivity, and teacher proximity directly predicted self-esteem, while self- -control indirectly predicted self-esteem through teacher proximity. Self-control and teacher proximity contributed directly to school success, and the indirect contribution of self- -control to school success through teacher proximity was also significant. The results of this research indicate the importance of the direct contribution of children's temperaments to their self-esteem and school success, and of its indirect contribution through the quality of the interaction with their teacher.