Informal and institutional barriers may limit teacher movement between charter schools and traditional public schools (TPSs). However, we know little about how teachers choose schools in areas with a robust charter school sector. This study uses qualitative data from 123 teachers to examine teachers' job decisions in three cities with varying charter densities: San Antonio, Detroit, and New Orleans. Our findings illuminate different types of segmentation and factors that facilitate and limit mobility between sectors. We find that structural policies within each sector can create barriers to mobility across charter schools and TPSs and that teachers' ideological beliefs and values serve as informal, personal barriers that reinforce divides between sectors. This study offers implications for policy in districts with school choice.