Large achievement gaps exist between high- and low-income students and between black and white students. This article explores one explanation for such gaps: income segregation between school districts, which creates inequality in the economic and social resources available in advantaged and disadvantaged students' school contexts. Drawing on national data, I find that the income achievement gap is larger in highly segregated metropolitan areas. This is due mainly to high-income students performing better, rather than low-income children performing worse, in more-segregated places. Income segregation between districts also contributes to the racial achievement gap, largely because white students perform better in more economically segregated places. Descriptive portraits of the school districts of high- and low-income students show that income segregation creates affluent districts for high-income students while changing the contexts of low-income students negligibly. Considering income and race jointly, I find that only high-income white families live in the affluent districts created by income segregation; black families with identically high incomes live in districts more similar to those of low-income white families. My results demonstrate that the spatial inequalities created by income segregation between school districts contribute to achievement gaps between advantaged and disadvantaged students, with implications for future research and policy.