Research shows that, once children are in school, the single most important factor affecting their achievement is the quality of their teachers. Schools with high percentages of low-income and minority students are consistently more likely to have teachers who are inexperienced, have lower basic academic skills or are not highly qualified. Addressing teacher quality is a critical strategy for closing the achievement gap, and an important priority of the No Child Left Behind Act. The Foundation has supported a number of initiatives to attract, support, and retain first-rate teachers in the schools that need them the most.