<p>In the classroom, teachers’ growth mindsets about students can support beneficial changes for students, but along the way, may also produce tension and conflict in student–teacher relationships. In the present research, we modified a measure used with adults to examine growth mindsets about emotional control and introduced it to the educational setting by examining associations between teachers’ mindsets about students’ intelligence and emotion. In addition, we investigated associations between teachers’ growth mindsets and student–teacher relational conflict from both teachers’ and students’ perspectives. Lastly, we evaluated the extent to which teachers’ growth mindsets were associated with students’ perceptions of relational conflict with teachers, even after first considering teachers’ conceptions of their relationships with students. Participants were 41 teachers (85.4% female) and 576 of their 4th- and 5th-grade students (51.1% female). Teachers reported their growth mindsets regarding students’ intelligence and emotion and the extent to which they experienced conflict in their individual relationships with students. Students also reported their perceptions of the relational conflict they experienced with teachers. Results indicated a moderate to strong correlation (<i>r</i> = .563) between the two mindsets, with teachers reporting stronger growth mindsets about intelligence than emotion<i>.</i> Additionally, teachers’ growth mindsets about students’ emotion were positively associated with students’ but not teachers’ perceived relational conflict. Findings suggest the importance of a shared growth mindset about emotion control in the classroom, especially in the context of power-differentiated relationships, and highlight the distinctive perspective of students about the quality of their relationships with teachers.</p>