Teachers make the greatest impact on students--what they learn, how they learn it, and what they do with it. Decades of research clearly demonstrate that a quality teacher, more than any other factor, enables students to overcome obstacles to learning like poverty and can even erase the achievement gap. The problem is that many teachers lack the skills and opportunities they need to become high-quality educators. And those who are most qualified work in schools where students are doing fairly well on their own. As standards rise, testing increases, and achievement stagnates, the American high school graduates too few students, and even those students lack the skills they need for life after high school. Thus, to help students meet the demands of college and an increasingly competitive global economy, they must be provided with skilled teachers who stay in the profession long enough to make a difference.