High teacher turnover imposes numerous costs on the schools and districts from which teachers depart. This study asks how schools respond to spells of high teacher turnover, and assesses organizational and human capital losses in terms of the changing composition of the teacher pool. Our analysis uses more than two decades of linked administrative data on math and ELA [English language arts] teachers at middle schools in North Carolina to determine the impacts of turnover across different policy environments and macroeconomic climates. We find that, even after accounting for school contexts and trends, turnover has marked, and lasting, negative consequences for teacher quality. Our results highlight the need for heightened policy attention to issues of teacher retention and working conditions.