This research analyzes the impact of the Adjusted Voucher Law´s school rankings on low-performing schools in Santiago, Chile, and provides evidence on the effects of the pressures of accountability systems on teacher policies and practices. The empirical strategy is based on the fact that schools are ranked according to their position on a set of thresholds. We used a generalization of the traditional regression discontinuity design for the case where treatment assignment is determined by variables. To gather information on teacher policies and practices, we conducted a survey of 4th-grade teachers in the Greater Santiago area. The results indicate that low-performing schools responded to the treatment by implementing policies that seek to improve their results in the short term. We also found no significant effects on teaching practices, suggesting that many of these changes are implemented top down from the school administrators, without involving teachers in the process.