This study investigates how school demographics and their interactions with policies affect the mobility behaviors of public school teachers with various human capital characteristics. Using data from North Carolina from 1995 to 2006, it finds that teachers' career stage and human capital investments dominate their decisions to leave public school teaching and school demographic characteristics play a dominant role in intra-system sorting. Schools serving at-risk children struggle to attract and retain teachers with desirable observable characteristics. We find evidence to suggest that across-the-board school-based pay-for-performance policies have small but significant associations with mobility decisions and appear to exacerbate inequities in the distribution of teacher qualifications. (Contains 5 tables and 7 figures.)