This article advances an interdisciplinary perspective on the factors influencing teacher quality, specifically defined as teachers’ practices and their interactions with students that can be shown to relate to student achievement. The article offers a view of teacher quality focused on teacher-child interactions that serve as explanatory mechanisms in predicting children’s achievement. Additionally, the article discusses two bodies of research from psychological science that illustrate the ways in which psychological principles and an overarching view of teachers as developing people may contribute to current debates about teacher quality.