Closing achievement gaps--disparities in academic achievement between minority and white students, and between low-income and higher-income students--has long been an unrealized goal of U.S. education policy. It has now been 60 years since the Supreme Court declared "separate but equal" schools unconstitutional in "Brown v. Board of Education." With income inequality at record levels, the interactions between poverty and race remain strong and troubling and continue to impede educational progress for many students. One result of such interactions is ongoing segregation at both the neighborhood and school levels. In this paper Garcia and Weiss use data from a recent representative cohort of U.S. students entering kindergarten to describe how segregated schools are by both race and income. Next, the authors compare the racial and socioeconomic status composition of those kindergarten classes with what they would look like if they represented the characteristics of the U.S. student body overall. Garcia and Weiss explore the differences in students' other characteristics based on the racial makeup of their own classes. Finally, Garcia and Weiss analyze how the students' academic performance changes over that first year, measured by their place on the score distribution in math, reading, and approaches to learning at entry in the fall and again in the spring, and by level of segregation in the school.