Private School vs. Public School: What Research Predicts

The number comes up at some point in most conversations about private school: the tuition. Twenty thousand dollars a year, or forty, or sixty for a well-known day school. The implicit question families are weighing is whether that number is buying something academically real — a measurably better education — or whether it’s buying class size, facilities, college counseling, and a social network. This is a reasonable question. The research that answers it is specific, published in peer-reviewed journals, and almost never appears in the discussions families actually have.

The private school vs public school research question deserves an honest treatment, because the honest treatment is more useful than either the private school advocacy version or the public school advocacy version.

Key Takeaways

• Raw test score comparisons show private school students outperforming public school students on virtually every measure. These comparisons are nearly meaningless because private school families are not a representative sample.
• When Christopher and Sarah Lubienski controlled for socioeconomic status in their 2006 NEPC analysis, the private school math advantage disappeared and in some categories reversed — public school students outperformed in math.
• OECD PISA 2022 data shows similar patterns internationally: once socioeconomic status is accounted for, public school students in many countries perform comparably or better than private school peers in core subjects.
• The advantages private schools reliably deliver — college placement, social capital, smaller classes, consistent teacher quality — are real but distinct from raw academic skill building.
• The decision framework should match your actual goals: “better academic outcomes” and “better college outcomes” are not the same question.

Why Raw Comparisons Mislead Almost Everyone

Private school vs public school research starts with a fundamental methodological problem. Families who choose private schools are not randomly selected from the population. They are, on average, higher-income, more highly educated, more likely to have two college-educated parents, more likely to provide extensive academic support at home, and more likely to have selected their neighborhood in part based on school quality. Their children arrive at private school already advantaged by every variable that predicts academic performance.

When you compare private school test scores to public school test scores without accounting for this, you’re largely comparing the output of advantaged families to the output of a more mixed population. The school itself may be contributing almost nothing to the difference. This is selection bias, and it’s the primary reason most published comparisons in popular media are misleading.

The correct comparison — and the one that researchers have been making carefully since the early 2000s — is: what does a student learn in a private school versus what would that same student learn in a comparable public school, holding family background constant? When you ask that question, the results change substantially.

What the Research on Private School vs. Public School Actually Shows

The study that most changed the research conversation was conducted by Christopher Lubienski and Sarah Theule Lubienski, published in 2006 by the National Education Policy Center (NEPC), and later expanded in their 2013 book The Public School Advantage. The Lubienskis used National Assessment of Educational Progress (NAEP) data — the “Nation’s Report Card,” which tests a national sample of 4th and 8th graders — and applied hierarchical linear modeling to account for student background variables including income, parental education, and race.

Their finding was striking. In reading, the private school advantage diminished substantially once background variables were controlled. In math, it disappeared entirely — and in some sub-analyses, public school students in demographically matched comparisons slightly outperformed private school peers. The schools that drove this reversal were, notably, elementary public schools that had adopted reform-focused instructional practices. The traditional private school advantage in math was an artifact of who attended, not what was taught.

Henry Braun and colleagues at the National Center for Education Statistics (NCES) replicated a similar analysis in 2006 using a different methodology on the same NAEP dataset and reached comparable conclusions: once demographic controls were applied, the private school achievement advantage was substantially smaller than raw comparisons suggested, and in math was negligible or reversed.

The OECD’s 2022 PISA data adds an international dimension. PISA tests 15-year-olds across 70+ countries in math, reading, and science. Their analysis of private-school-attending versus publicly-schooled students found that in most OECD countries, the private school advantage in academic performance disappeared or reversed once socioeconomic status of students and schools was controlled. The average difference in favor of private school students in raw scores was approximately 30 PISA points — roughly equivalent to one school year of learning. After controlling for socioeconomic status, the difference was close to zero across most countries.

Data Source	Raw Private School Advantage	After Controlling for SES	Subject
Lubienski & Lubienski (2006 NAEP)	Significant in reading and math	Disappears in math; small in reading	4th and 8th grade
Braun et al. (2006 NCES)	Significant in reading and math	Substantially reduced; negligible in math	4th and 8th grade
NAEP 2022 (private vs. public comparison)	Private +18 pts reading, +15 pts math (raw)	Not fully adjusted in public release	4th and 8th grade
OECD PISA 2022	Private +30 pts (raw average, OECD)	Near zero in most countries after SES control	15-year-olds, math/reading/science
Carbonaro & Covay (2010, Sociology of Education)	Positive in reading	Disappears for most private school types	10th graders

The one consistent exception in U.S. research is Catholic schools. Catholic high schools have repeatedly shown modestly positive effects in reading and graduation rates even after demographic controls — an effect first identified by James Coleman in his landmark 1982 study and replicated in subsequent work. The likely mechanism is what Coleman called “social capital” — the dense network of family and community relationships organized around Catholic parish life. This is a structural effect, not an instructional quality effect, and it applies specifically to Catholic schools rather than to private schools as a category.

What to Actually Do With This Information

Reframe the Question You’re Actually Asking

Private school vs public school research answers a specific question: does a private school produce better academic skill development than a comparable public school, holding family background constant? The answer is: mostly not, and specifically not in math.

But families often aren’t really asking about academic skill development in isolation. They may be asking about: college placement rates; consistency of teacher quality; smaller class sizes; particular values or culture; sports or arts programs; safety and disciplinary environment; peer social environment; or continuity across K–12 years. Those are legitimate questions. They just aren’t questions that academic outcome research answers.

Get honest about which question you’re actually asking before spending $30,000 per year on an answer to a question that isn’t the one you meant to ask.

Evaluate the Specific School, Not the Category

The variance within private schools is enormous. A well-funded independent day school with 15 students per class, experienced certified teachers, and robust academic support is a different institution from a small faith-based school charging $8,000 per year with high teacher turnover and no learning support staff. Similarly, the variance within public schools is enormous. A well-resourced suburban public school in a high-property-tax district may provide better academic preparation than an average private school at twice the cost.

Research the specific institution’s teacher retention, curriculum, class sizes, and college outcomes. Ask for the school’s standardized test results broken down by student subgroup. If the private school’s strong results are driven by a highly selected, affluent student body, you’re paying for peer selection, not instruction.

Understand What Private Schools Do Reliably Deliver

College placement — particularly to selective colleges — is an area where private school advantage is real and harder to explain away by demographics alone. Private schools typically have dedicated college counselors in ratios that public schools cannot match (a topic connected directly to the broader counselor shortage). They often have established relationships with admissions offices. They produce students whose extracurricular portfolios, teacher recommendation networks, and interview preparation are consistently stronger — not because the students are smarter, but because the school’s resources are explicitly organized around this outcome.

Whether that outcome is worth the tuition depends on your specific goals. If your goal is selective college placement and you can afford it without financial stress, private schools do tend to deliver on that. If your goal is for your child to be a more capable mathematician or reader at age 14, the research says your neighborhood public school with a strong math program may achieve the same result.

Pay Attention to What Happens to Learning Support Students

Private schools can legally decline to admit students with significant learning differences, and many do. They are not bound by IDEA (Individuals with Disabilities Education Act) the way public schools are. If your child has an IEP, a 504 plan, dyscalculia, dyslexia, or a processing difference that requires specialized instruction, a private school without a documented commitment to and staffing for learning support is likely to be a worse fit than a public school legally required to provide free appropriate public education. See IEP vs. 504 Plan: What Parents Need to Know for more on those legal protections and what to look for.

Factor In the Opportunity Cost

$20,000 per year invested in a child’s education from kindergarten through 12th grade is $260,000 before inflation. $40,000 per year is $520,000. For most families, that is a significant fraction of retirement savings, a down payment, or a sibling’s education fund. Research on outcome differences that largely disappear once background is controlled should make that figure feel more consequential — not as a reason to dismiss private school, but as a reason to be specific about what you’re actually buying.

The relevant comparison is not “private school child vs. public school child.” It’s “this specific private school, for this specific child, against this specific public alternative, given what else we could do with that money.” For some families in some districts, private school is clearly the better investment. For many, the research suggests the same family resources invested in tutoring, enrichment programs, and strong summer learning against a solid public school background produces comparable or better outcomes at lower cost.

For more on what standardized tests actually predict about academic outcomes, see standardized tests: what scores predict about kids.

What to Watch for Over the Next 3 Months

If you’re evaluating a school switch — either into or out of private school — use the following framework.

Month 1: Separate the goals. Write two lists: academic skill development goals, and non-academic goals (culture, peers, college outcomes, safety). Research which goals the research supports private schools for and which it doesn’t.

Month 2: Request performance data from the specific schools you’re considering. Ask public schools for NAEP-aligned assessment results. Ask private schools for any standardized testing data they use internally and their college placement record broken down by selectivity tier, not just “98% of graduates attend college.”

Month 3: If you have children with learning differences or consider yourself likely to in the future, research each school’s learning support infrastructure specifically. A private school without an IEP compliance obligation that has no learning support staff is a real risk for a family whose children include statistically likely learning difference profiles.

Frequently Asked Questions

Don’t private schools just have better teachers?

Not systematically. Private schools are exempt from many state certification requirements, which means their teacher pool may include both highly experienced educators who chose private school culture and uncredentialed individuals working for lower salaries. Public school teachers are required to meet certification standards; private school teachers are not in most states. Teacher quality varies enormously within both sectors, and the private school advantage on this dimension is not consistent across schools.

What does research say about private school and long-term earnings?

The research here is mixed and heavily confounded. Studies that track private school graduates to adulthood find higher average earnings — but these studies face the same selection bias problem as academic outcome studies. Families with higher income and social capital tend to produce children with higher adult earnings regardless of school type. Studies attempting to control for these factors find reduced or negligible private school earnings advantages.

Are religious private schools different from secular private schools in outcome research?

Yes. Catholic schools specifically have the strongest evidence base for positive effects even after controlling for demographics, with the effect most pronounced for Black and Hispanic students in urban settings. This is attributed partly to structured learning environment and partly to community social capital. Secular independent schools have less consistent evidence for above-expectation outcomes once demographics are controlled.

Does private school matter more for some grade levels than others?

High school has the strongest research base and the strongest case for private school effects — particularly for college preparation and placement. The evidence base for private school effects in elementary grades is weaker. If resources are limited, the research modestly favors prioritizing private school at the high school level if college placement is the primary goal.

What should I ask a private school that I can’t find online?

Ask for: teacher retention rates for the past three years; the student-to-counselor ratio; standardized testing data broken down by subgroup; the percentage of students who receive financial aid; and — if relevant — the school’s approach to students with identified learning differences, including whether they have any staff trained in dyslexia intervention or ADHD support.

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About the author

Ricky Flores is the founder of HiWave Makers and an electrical engineer with 15+ years of experience building consumer technology at Apple, Samsung, and Texas Instruments. He writes about how kids learn to build, think, and create in a tech-saturated world. Read more at hiwavemakers.com.

Sources

1. Lubienski, C., & Lubienski, S. T. (2006). Charter, Private, Public Schools and Academic Achievement: New Evidence from NAEP Mathematics Data. National Education Policy Center. https://nepc.colorado.edu/publication/charter-private-public-schools-and-academic-achievement

2. Braun, H., Jenkins, F., & Grigg, W. (2006). Comparing Private Schools and Public Schools Using Hierarchical Linear Modeling. National Center for Education Statistics, NCES 2006-461. https://nces.ed.gov/pubsearch/pubsinfo.asp?pubid=2006461

3. OECD. (2023). PISA 2022 Results (Volume I): The State of Learning and Equity in Education. OECD Publishing. https://doi.org/10.1787/53f23881-en

4. Coleman, J. S., Hoffer, T., & Kilgore, S. (1982). High School Achievement: Public, Catholic, and Private Schools Compared. Basic Books. (Seminal source on Catholic school effects and social capital.)

5. Carbonaro, W., & Covay, E. (2010). “School sector and student achievement in the era of standards-based reforms.” Sociology of Education, 83(2), 160–182. https://doi.org/10.1177/0038040710367934

6. National Center for Education Statistics. (2022). NAEP 2022 Reading and Mathematics Assessments. U.S. Department of Education. https://nces.ed.gov/nationsreportcard/

7. Lubienski, C., & Lubienski, S. T. (2013). The Public School Advantage: Why Public Schools Outperform Private Schools. University of Chicago Press.