Why does the United States not have the teachers it needs? The media typically focus on a looming teacher shortage, but this volume of the Brookings Papers on Education Policy goes beyond the question of quantity to examine why American schools must scramble to find enough well-prepared and effective teachers. There are perennial teacher shortages in certain fields, especially mathematics and the sciences. Many teachers are assigned to subjects in which they have neither a major nor a minor. Which is more important in training teachers: pedagogical knowledge or content knowledge? Furthermore, a disproportionate number of teachers who are uncertified and inexperienced are assigned to urban and poor schools. Is there anything states and districts can do to change this bleak picture? These and many other issues related to teacher education, teacher preparation, teacher assignment, and teacher compensation are explored here. The controversies studied have been raging in policy circles for many years. While the contributors do not issue any ringing policy manifestos their clear and cool analysis sheds enough light on these dilemmas to help guide the way to better approaches to teacher training, compensation, and retention.