This article assesses the association between the Title I School Improvement Grant (SIG) program’s personnel replacement policy and teacher employment patterns within an urban school district. Hannan and Freeman’s population ecology model allowed the authors to consider schools within districts as individual organizations nested within a larger organization. The data are drawn from employment records of 2,470 teachers who worked in 19 high schools in a single school district from 2006 to 2011. The personnel replacement policy of the Title I SIG program appears to have reinforced, and in some cases intensified, existing patterns of teacher selection, retention, and migration.