About

Sean Reardon is a professor associated with the Educational Opportunity Project at Stanford University, which has developed the first national database of academic performance in the United States. His research focuses on measuring educational opportunity across every community in America, analyzing trends in academic achievement, and understanding disparities in educational outcomes. Reardon contributes to creating applications, research reports, and interactive articles that enable exploration and understanding of educational data. His work includes examining school and neighborhood segregation, racial and economic disparities in education, and the impact of various factors on academic progress and achievement gaps. Through his involvement in the Educational Opportunity Project and related initiatives, Reardon plays a key role in advancing knowledge about educational opportunity, segregation, and achievement trends in U.S. schools.

Research topics

• Sociology
• Psychology
• Demography
• Socioeconomics
• Geography
• Political Science
• Mathematics education
• Gender studies
• Economics
• Demographic economics
• Medicine

Selected publications

• A Longitudinal Portrait of California’s Kindergarten English Learners & Their Learning Outcomes

  AERA Open · 2025-02-26

  articleOpen access

  California’s K–12 funding and instructional policies for English learners have changed significantly over the past two decades. This paper uses student-level longitudinal data from 2006 to 2019 to examine the learning outcomes of successive cohorts of students who were classified as English learners in kindergarten as they progressed through California’s changing public school system. First, we find ELs grew more diverse linguistically over time. Second, we find that their third-grade achievement improved in math and English language arts and achievement gaps narrowed in both subjects. Third, we find that more recent cohorts reported slightly higher rates of English proficiency acquisition by the end of grade 5. Finally, we find that the proportion who were reclassified by grade 5 increased dramatically for the first two cohorts of our study but then remained constant for the next five years. In the most recent cohort we can observe, only 53% of students who entered kindergarten as ELs were reclassified by the end of grade 5.

  PublisherDOI

• School District and Community Factors Associated with Test Score Declines During the COVID-19 Pandemic

  Teachers College Record The Voice of Scholarship in Education · 2025-07-01 · 1 citations

  article

  Using data from approximately 7,800 school districts, we show that test score declines during the pandemic were large and highly variable. We find that test score declines were larger in lower-income and minority districts, but that within districts, White students and non–economically disadvantaged students lost about the same amount of ground as Black, Hispanic, and economically disadvantaged students. We find that the test score declines were larger in districts where more of the 2020–2021 school year was spent in remote or hybrid instructional modalities, where students had less access to broadband access at home, where the pandemic led to larger disruptions to local social and economic activity, and in communities where trust in government institutions was low.

  PublisherDOI

• Cross-National Comparison of the Relative Size of Lower-Tail and Upper-Tail SES Achievement Gaps

  AERA Open · 2024-01-01

  articleOpen accessSenior author

  Cross-national studies on socioeconomic status (SES) achievement gaps have focused on the size of the gap and given less attention to where in the SES distribution the achievement gap tends to be relatively large within a society, and whether this location varies across countries. We estimate the relative size of achievement gaps between students at the 50th and 10th percentiles versus the 90th and 50th percentiles of SES distribution within a society, using the Organisation for Economic Co-operation and Development (OECD) Programme for International Student Assessment (PISA) data. We find OECD countries vary in the size of the ratio of achievement gaps at lower-tail SES and upper-tail SES. Our multivariate analyses show that the ratio is positively associated with within-country patterns of economic inequality, measured by the ratio of income inequality and the ratio of segregation at lower-tail and upper-tail SES. We do not find evidence of an association between the achievement gap ratio and patterns of educational stratification.

  PublisherDOI

• Is Separate Still Unequal? New Evidence on School Segregation and Racial Academic Achievement Gaps

  American Sociological Review · 2024 · 88 citations

  1st authorCorresponding
  • Mathematics education
  • Psychology

  U.S. public schools are racially and economically segregated. Prior research shows that the desegregation of Southern schools beginning in the 1960s led to significant benefits for Black students. Less clear, however, is whether segregation today has the same harmful effects as it did 50 years ago and through what mechanisms segregation continues to affect achievement. We estimate the effects of current-day school segregation on racial achievement gaps using 11 years of data from all U.S. public school districts. We find that racial segregation is strongly associated with the magnitude of achievement gaps in 3rd grade and the rate at which gaps grow from 3rd to 8th grade. The association of racial segregation with achievement-gap growth is completely accounted for by racial differences in school poverty. Thus, racial segregation is harmful because it concentrates minority students in high-poverty schools, which are, on average, less effective than lower-poverty schools. Exploratory analyses show that segregation-related between-school differences in teacher characteristics are associated with unequal learning rates and account for roughly 20 percent of the effect of Black–White racial differences in exposure to poverty. Further research is needed to identify mechanisms linking school segregation to achievement-gap growth.

  PublisherOA PDFDOI

• Education Research-Practice Partnerships: Impacts and Dynamics

  Peabody Journal of Education · 2024-05-26 · 6 citations

  articleSenior author

  The emerging literature on research-practice partnerships in education explains the conditions under which these partnerships operate to achieve the desired impact. This study adds to that literature base by exploring variation in the perceived impacts across three partnerships whose goal was improving achievement for multilingual learner students. To examine these partnerships, we posit a conceptual framework that defines partnership impacts and associated supportive dynamics within the partnership. We use this framework to guide our analysis of interviews and observations from three partnerships. Our study finds (1) practitioners and researchers' motivations to engage in the RPP are different but complementary; (2) practitioners and researchers perceive the RPP as impacting their capacity either to make decisions that change policy and practice or to develop research that is relevant for theory and practice; (3) both researchers and practitioners agree that consistent communication through meetings and reliable funding supports the RPP. Implications for the field and ideas for further research are discussed.

  PublisherDOI

• Federal Pandemic Relief and Academic Recovery

  SSRN Electronic Journal · 2024-01-01

  articleOpen access
  PublisherDOI

• Federal Pandemic Relief and Academic Recovery

  National Bureau of Economic Research · 2024-09-01 · 5 citations

  reportOpen access

  We measure the effect of district use of federal pandemic relief during the 2022-23 school year for a sample of more than 5000 districts in 29 states.We rely on several plausibly exogenous sources of variation in federal grants: differences in state Title I funding formulas, estimation error in Census local area poverty rates and differences in eligibility for federal Title I and subsidized lunch eligibility.We find that each $1000 in spending per student was associated with a .0086SD improvement in math and a .0049SD improvement in reading.Both are consistent with a recent meta-analysis of spending impacts by Jackson and Mackevicius (2023).As a placebo test, we find no relationship between federal dollars that were not yet spent during the 2022-23 year.We also find similar results using synthetic control group methods to compare high-poverty districts with high and low amounts of federal aid, but with similar trends in achievement through 2022.Because the federal aid was targeted at higher poverty districts, we find the federal dollars not only contributed to the recovery, but also helped narrow the gaps in achievement which had widened during the pandemic.

  PublisherDOI

• It Is Surprisingly Difficult to Measure Income Segregation

  Demography · 2023-08-22 · 4 citations

  articleOpen accessSenior author

  Recent studies have shown that U.S. Census- and American Community Survey (ACS)-based estimates of income segregation are subject to upward finite sampling bias (Logan et al. 2018; Logan et al. 2020; Reardon et al. 2018). We identify two additional sources of bias that are larger and opposite in sign to finite sampling bias: measurement error-induced attenuation bias and temporal pooling bias. The combination of these three sources of bias make it unclear how income segregation has trended. We formalize the three types of bias, providing a method to correct them simultaneously using public data from the decennial census and ACS from 1990 to 2015-2019. We use these methods to produce bias-corrected estimates of income segregation in the United States from 1990 to 2019. We find that (1) segregation is on the order of 50% greater than previously believed; (2) the increase from 2000 to the 2005-2009 period was much greater than indicated by previous estimates; and (3) segregation has declined since 2005-2009. Correcting these biases requires good estimates of the reliability of self-reported income and of the year-to-year volatility in neighborhood mean incomes.

  PublisherOA PDFDOI

• Uneven Progress: Recent Trends in Academic Performance Among U.S. School Districts

  American Educational Research Journal · 2023-01-16 · 25 citations

  articleSenior author

  We use data from the Stanford Education Data Archive to describe district-level trends in average academic achievement between 2009 and 2019. Although on average school districts’ test scores improved very modestly (by about 0.001 standard deviations per year), there is significant variation among districts. Moreover, we find that average test score disparities between nonpoor and poor students and between White and Black students are growing; those between White and Hispanic students are shrinking. We find no evidence of achievement-equity synergies or trade-offs: Improvements in overall achievement are uncorrelated with trends in achievement disparities. Finally, we find that the strongest predictors of achievement disparity trends are the levels and trends in within-district racial and socioeconomic segregation and changes in differential access to certified teachers.

  PublisherDOI

• School Racial Segregation and the Health of Black Children

  PEDIATRICS · 2022-04-18 · 36 citations

  articleOpen access

  OBJECTIVES: Few researchers have evaluated whether school racial segregation, a key manifestation of structural racism, affects child health, despite its potential impacts on school quality, social networks, and stress from discrimination. We investigated whether school racial segregation affects Black children's health and health behaviors. METHODS: We estimated the association of school segregation with child health, leveraging a natural experiment in which school districts in recent years experienced increased school segregation. School segregation was operationalized as the Black-White dissimilarity index. We used ordinary least squares models as well as quasi-experimental instrumental variables analysis, which can reduce bias from unobserved confounders. Data from the Child Development Supplement of the Panel Study of Income Dynamics (1997-2014, n = 1248 Black children) were linked with district-level school segregation measures. Multivariable regressions were adjusted for individual-, neighborhood-, and district-level covariates. We also performed subgroup analyses by child sex and age. RESULTS: In instrumental variables models, a one standard deviation increase in school segregation was associated with increased behavioral problems (2.53 points on a 27-point scale; 95% CI, 0.26 to 4.80), probability of having ever drunk alcohol (0.23; 95% CI, 0.049 to 0.42), and drinking at least monthly (0.20; 95% CI, 0.053 to 0.35). School segregation was more strongly associated with drinking behaviors among girls. CONCLUSIONS: School segregation was associated with worse outcomes on several measures of well-being among Black children, which may contribute to health inequities across the life span. These results highlight the need to promote school racial integration and support Black youth attending segregated schools.

  PublisherOA PDFDOI

Recent grants

• Collaborative Research: Measuring Spatial Segregation

  NSF · $135k · 2005–2008

Frequent coauthors

• Demetra Kalogrides

  Stanford University

  22 shared

• Stephen W. Raudenbush

  University of Chicago

  17 shared

• Richard J. Murnane

  15 shared

• Stephen L. Buka

  13 shared

• Erin M. Fahle

  Stanford University

  12 shared

• Joseph B. Townsend

  Stanford University

  12 shared

• Scott P. Novak

  11 shared

• Andrew Ho

  10 shared

Labs

• Center for Education Policy AnalysisPI

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Education

• B.A., Program of Liberal Studies; Minor in Honors Mathematics

  University of Notre Dame

  1986

• M.A., International Peace Studies

  University of Notre Dame

  1991

• Other, Educational Administration, Planning and Social Policy

  Harvard Graduate School of Education

  1992

• Other, Educational Administration, Planning, and Social Policy

  Harvard Graduate School of Education

  1997

Awards & honors

• Elected Member, The American Academy of Arts and Sciences
• Elected Member, National Academy of Education