Teachers are central to the quality and equity of an education system. However, they have been largely overlooked by the modern sociology of education. To raise awareness of teachers and their importance to sociological inquires, this chapter reviews the literature with the aim of answering three questions. First, how important are teachers to student learning? Second, what observable teacher characteristics foster student learning gains? Third, who self-selects into the teaching profession – and what are the consequences of this for the supply of high-quality teachers?