This paper focuses on what research has shown about the impact of teacher quality on student achievement, the connection between quality and observable teacher characteristics and traits, and what all this might mean for teacher policy. Teacher quality is the largest factor contributing to student achievement in schools, but teacher characteristics such as education level and certification status are poor proxies for teacher quality. This paper explains the weak relationship between teacher effectiveness and how teacher compensation currently is determined. The author discusses policies designed to act on the differences that exist between teachers, and concludes with possible pathways for improving teacher quality. [An extensive list of resources is included.]