Struggling schools that come under increased accountability pressure face a number of challenges, including changing instructional policies and practices to facilitate student improvement. But what effect does school accountability have on teachers’ mobility decisions? This study is the first to exploit policy variation within the same state to examine the effects of school accountability on teacher job changes. Using student-level data from Florida State the authors measure the degree to which schools and teachers were “surprised” by the change in Florida’s school grading system (A+ Plan for Education) in the summer of 2002— what they refer to as an “accountability shock.” They observed the mobility decisions of teachers in the years before and after the school grading change and found over half of all schools in the state experienced an accountability “shock” due to this grading change.  Teachers were more likely to leave schools facing increased accountability pressure; even more likely to leave schools shocked downward to a grade of “F”; and less likely to leave schools facing decreased accountability pressure. Schools facing increased accountability pressure also saw a rise in the average quality of the teachers who stayed.  If these schools were able to retain more of their high- quality teachers, perhaps through increased incentives to remain in the school, the performance gains associated with school accountability pressure could be greater than those already observed.