This paper describes the prevalence of highest-performing teachers in ten purposely selected districts across seven states. The overall patterns indicate that low-income students have unequal access, on average, to the district’s highest-performing teachers at the middle school level but not at the elementary level. However, there is evidence of variation in the distribution of highest-performing teachers within and among the ten districts studied. Some have an under-representation of the highest-performing teachers in high-poverty elementary and middle schools. Others have such under-representation only at the middle school level, and one district has a disproportionate share of the district’s highest-performing teachers in its high-poverty elementary schools.

There is growing concern that students from low-income and minority backgrounds have relatively less access to teacher quality. It is well documented that schools with more disadvantaged students tend to have teachers with weaker qualifications in terms of experience, teacher test scores, post-baccalaureate coursework, and certification. However, with the exception of experience in the first few years of teaching, the teacher qualifications that have been shown to be inequitably distributed are only weakly if at all associated with teacher performance in the classroom.

The strongest predictor of a teacher’s on-the-job performance in a given year is that teacher’s past performance in the classroom. Thus those who want to assure that economically disadvantaged students have access to teachers who are at least as good as those available to students in more advantaged circumstances need to attend to the distribution of teacher effectiveness, measured in terms of classroom performance, rather than to the distribution of teacher credentials.

There are structural reasons to expect teachers to be unevenly distributed across schools based on credentials. Within districts, teachers with more seniority receive preference in teaching assignments, and across districts teachers with experience and favored credentials have advantages when competing for openings. Thus teachers tend to migrate from more to less challenging schools as they accumulate seniority and advanced course credits. However, since few school districts systematically collect or use data on teacher effectiveness and effectiveness is not strongly correlated with observable teacher credentials, the mechanisms that would result in the most effective teachers being in the most advantaged schools are not clear. As the education policy landscape shifts from a focus on assuring equitable access to teacher quality measured by credentials to equitable access to teacher quality measured by performance, it will be important to know whether there are predictable patterns of sorting by teacher effectiveness based on school demographics. For example, policymakers might respond differently if we found that the most effective teachers were disproportionately represented in lower-poverty schools than if there were no systematic relationship between teacher effectiveness and school demographics. This paper adds to our knowledge of how teacher performance is distributed across schools by describing the prevalence of highest-performing teachers across schools of higher and lower poverty levels in ten school districts across seven states. Analyses in this memo pertain to these ten districts.