Understanding what makes an effective teacher, as well as how teachers sort by their effectiveness across schools, is central to understanding and addressing student achievement gaps. Prior studies have found substantial sorting of teachers across schools, with the schools with the highest proportions of poor, non-white, and low-scoring students having the least qualified teachers as measured by certification, exam performance, and inexperience. Yet there have been substantial changes in the educational policy landscape over the past five years. In this paper, the authors examine these changes, asking how the distribution of teachers has changed in recent years and what the implications of these changes are for students. The authors address these questions using data on New York City teachers, students, and schools. While the findings may be specific to New York City, they may mirror changes in other large urban districts, many of which have seen similar policy changes over the past decade. The authors find that measurable characteristics of teachers are more equal across schools in 2005 than they were in 2000. Schools with large proportions of poor students and students of color, on average, have teachers whose observable qualifications are much stronger than they were five years ago. Nonetheless, a meaningful number of schools with large proportions of poor students did not demonstrate such improvement. The authors find that changes in these observed qualifications of teachers account for a modest improvement in the average achievement of students in the poorest schools. More important, the results suggest that recruiting teachers with stronger observed qualifications--for example, math SAT scores or certification status--could substantially improve student achievement. (Contains 6 tables, 9 figures, and 9 footnotes.)