This article from authors at the Center for Education Policy Research at Harvard University and Brown University examines how demographic matching between teachers and students influences students' social-emotional, academic, and behavioral outcomes. Using student fixed-effects models to track changes over time in the proportion of teachers who shared students' race and gender, the study estimates the effects of teacher-student demographic matching in K–12 classrooms. The findings show that students, particularly Black female students, demonstrate stronger grit and interpersonal self-management when taught by teachers who share their race and gender. The study also finds that demographic matching is associated with fewer absences and suspensions, with the strongest effects observed among Black students. The authors conclude that increasing teacher diversity can meaningfully support students' social-emotional development and school engagement, adding to the growing body of evidence for policies and practices that diversify the educator workforce.