"As part of its effective-teaching initiative, Intensive Partnerships for Effective Teaching, the Bill & Melinda Gates Foundation has partnered with three urban school districts across the United States and a group of four charter management organizations to undertake a set of strategic human-capital reforms. The reforms are intended to improve teachers' overall effectiveness and to ensure that low-income minority (LIM) students have access to highly effective teachers. Lack of access to effective teaching has been identified as a possible contributor to the well-documented achievement gap between LIM students and their more-advantaged peers. This report attends to the distribution of effective teachers within and across schools in the Intensive Partnership sites. The authors first examine the trends in the distribution of effective teachers between LIM students and other students. They also examine whether any of a variety of mechanisms can explain changes in LIM students' access to effective teaching. These mechanisms include increasing the percentage of LIM students whom effective teachers teach, increasing the effectiveness of teachers with large percentages of LIM students, and replacing less effective teachers of LIM students with more-effective teachers."--