Over the past decade, education reformers have focused much of their attention on raising teacher quality. This focus on individual teachers has caused policymakers to lose sight of the importance of the organizational contexts in which teachers work and students learn. The quality of a school's teaching staff is greater than the sum of its parts. School environments can enable teachers to perform to their fullest potential or undercut their efforts to do so. State education agencies and boards of education that are working to improve instruction across school systems would do well to recognize the interconnected nature of teachers' work and the environments in which they perform their craft.