Student mobility and school segregation are two important issues with significant equity implications for urban school districts that are often addressed separately. This article examines the relationship between student mobility and school segregation. The findings indicate that more segregated schools typically have smaller within-school achievement gaps, a lower proportion of proficient students, a higher proportion of low-income and minority students, and higher nonstructural mobility rates (especially within-year mobility) than less segregated schools. The results also suggest that, regardless of the timing of school changes, high levels of achievement segregation are a significant predictor of student mobility. Policy implications are discussed.