From a nationwide perspective, the number of teachers leaving schools in the United States – frequently referred to as teacher turnover – is not very large. Between 2003-2004 and 2004-2005, for instance, 83.5% of teachers stayed in the same school, while only 8.1% transferred between schools and 8.4% left teaching (Marvel et al.,2007). However , averages rates hide the fact that some schools lose teachers frequently, particularly schools serving black and low-achieving students (Hanushek et al., 2004; Boyd et al., 2007). High rates of teacher turnover can destabilize the learning environment in schools, disrupting instructional continuity in classrooms and jeopardizing the educational experience of students, many of whom are already at a disadvantage (Shields et al., 1999; Loeb et al.,2005). Administrators may find it difficult to implement policies or make changes if the teaching force in a school is in constant flux.