The literature on effective schools emphasizes the importance of a quality teaching force in improving educational outcomes for students. In this article we use value-added methods to examine the relationship between a school's effectiveness and the recruitment, assignment, development, and retention of its teachers. Our results reveal four key findings. First, we find that more effective schools are able to attract and hire more effective teachers from other schools when vacancies arise. Second, more effective schools assign novice teachers to students in a more equitable fashion. Third, teachers who work in schools that were more effective at raising achievement in a prior period improve more rapidly in a subsequent period than do those in less effective schools. Finally, we find that more effective schools are better able to retain higher-quality teachers. The results point to the importance of personnel and, perhaps, school personnel practices for improving student outcomes.