The Empirical Study On Charter School Outcomes Just Got Updated. The Results Are Inconvenient.

The Update To The Record

The Center for Research on Education Outcomes at Stanford University published its 2026 update on charter school student outcomes in mid-January. The update extends the longitudinal record by adding three additional years of student-level data, drawing from a sample of approximately 1.9 million students across twenty-four state-level matched comparison groups. The methodology, refined since the center's original 2009 study, has become the methodology the broader research community treats as the benchmark for evaluating charter school performance against traditional public school performance for comparable student populations.

The results extend a pattern the policy literature has been slow to engage with on its merits. In the updated sample, charter school students outperform their traditional public school peers in reading by an average of seventeen additional days of learning per academic year, and in mathematics by an average of twenty-three additional days of learning per academic year. The effect sizes are larger for low-income students, larger still for Black students, and larger again for English language learners. The literature is clear.

The Effect Size That The Policy Debate Will Not Discuss

The effect size for Black students in the updated CREDO data is approximately 0.21 standard deviations in reading and 0.30 standard deviations in mathematics per academic year, accumulating across multiple years of charter enrollment. The effect size for Hispanic students is comparable. The effect size for the broader student population is smaller, on the order of 0.06 to 0.08 standard deviations. The disparity in effect sizes by student demographic is the finding that the policy debate has had the most difficulty engaging with on its merits.

Consider this. The same policy intervention, the same school model, the same teaching approach, produces materially larger gains for the student populations whose educational outcomes have been the focus of fifty years of policy debate about persistent achievement gaps. The data contradicts the narrative that has dominated education policy discussion since the publication of A Nation at Risk in 1983 and that has hardened since the No Child Left Behind era. The data is what the data is.

The Soft Bigotry The Policy Establishment Will Not Confront

The soft bigotry of low expectations is still bigotry. The argument that the policy establishment has used to slow charter expansion in jurisdictions where the achievement gap is largest, that charter schools cream-skim the most motivated students from traditional public schools, has been examined repeatedly in the CREDO methodology. The methodology pairs each charter student with a traditional public school student matched on prior achievement, demographic characteristics, free-and-reduced-lunch eligibility, and English language learner status. The matched comparison addresses the selection critique directly. The matched comparison continues to find the same effect sizes.

I will say what others will not. The opposition to charter school expansion in the districts where charters produce the largest gains for Black and Hispanic students is opposition that prioritizes institutional protection of the traditional public school monopoly over the measurable educational outcomes of the students who would be enrolled. The opposition is honest, in the sense that the institutional incumbents would defend their position on the merits. The opposition is also, in plain reading, opposition that the data does not vindicate.

What The Data Does Not Say

The data does not say that charter schools are uniformly better than traditional public schools. The CREDO data shows considerable variance across charter networks, across geographic markets, and across individual schools. The variance is substantial. Approximately one quarter of charter schools in the sample produce outcomes worse than the matched traditional public school comparison. Approximately one quarter produce outcomes substantially better. The remaining half produce outcomes broadly comparable. The aggregate effect size reflects the distribution.

The implication is that charter school quality control matters. The states with the most rigorous charter authorization standards, including Massachusetts, Indiana, and Texas, produce charter networks whose effect sizes are larger than the national average. The states with the least rigorous authorization standards, including Arizona during the period the study examines, produce charter networks whose effect sizes are smaller. The variance is not random. The variance is institutional.

The Implication For Policy

The implication for policy is straightforward and is in the same direction as the implication the CREDO findings have implied since 2009. The states whose authorization standards produce the largest effect sizes should expand. The states whose authorization standards do not should reform their standards before expansion. The teacher unions that have invested heavily in opposing charter expansion in the states with the largest achievement gaps should engage with the empirical record on its merits.

This deserves scrutiny. The policy debate has, for two decades, been treated as a debate about institutional preference rather than as a debate about empirical outcomes. The debate, treated as a debate about outcomes, has a clearer answer than the institutional debate has acknowledged. The clearer answer points in a direction the institutional incumbents have spent significant resources resisting. The resistance is the resistance. The data is the data.

What I Will Tell My Students

What I will tell my students, when we cover the CREDO update in the seminar on race and education policy this spring, is what I tell them about every empirical literature we examine. The data is the foundation. The policy debate is what gets built on the foundation. When the policy debate diverges from the foundation, the divergence is the analytical question, not the answer. The students will, I expect, push back against the implications. I will ask them to push back with the empirical alternative they prefer.

My parents came from Nigeria. They did not come here to be victims. They came here because the country offered a structural opportunity that the country they left did not offer. The structural opportunity in American education today is the opportunity that the charter school model, in its better implementations, has been delivering for the student populations the country has historically failed. The data has been pointing to this for fifteen years. The policy is catching up slowly. The students do not have fifteen more years.