This article has been updated to reflect 2026 data and recent developments.
A new report card came out for charter schools, courtesy of Mathematica Policy Research. The study was considered to be the most comprehensive, longitudinal study on charter school networks to date, and it offered valuable information on whether these public schools were serving the purpose originally intended for them. While data was somewhat mixed throughout the study, there were a few key facts that could be taken from the research to explain why some charter schools are more effective than others.
More recent research continues to examine the same question. The Center for Research on Education Outcomes at Stanford University published its third National Charter School Study in 2023, examining the academic progress of charter school students compared with students in traditional public schools. The study found positive average effects for charter students in both reading and mathematics, although results continued to vary among schools and student groups.
The CMO and the Study
The Mathematica study revolves around data collected on charter school management organizations, or CMOs. These organizations serve as networks that operate multiple charter schools. At the time of the study, there were around 130 CMOs across the country that were responsible for meeting the needs of approximately 250,000 students. While this number did not encompass all of the charter schools in operation, the number of schools overseen by CMOs had been growing. According to Mathematica, by 2012 there were at least 130 CMOs nationwide, accounting for about 16 percent of all charter schools.
CMOs remain an important part of the charter sector in 2026. In 2025, the federal Charter Schools Program awarded $263 million over five years to 22 CMO grantees to replicate and expand 147 high-quality charter schools, according to the National Alliance for Public Charter Schools.
According to a press release on Mathematica’s website, the study selected 40 CMOs to examine management practices and instructional methodology at these organizations to determine how effective they were in impacting the achievement of students within their schools. Of those 40, 22 networks provided sufficient data for accurate analysis. The core of the study was achievement in the middle school years, which these 22 CMOs were able to adequately provide numbers for in at least four of the schools included in each network.
Many CMOs are primarily designed to replicate educational approaches that work particularly well among disadvantaged students. This is one of the reasons charter schools are a popular choice in communities with underachieving public schools, where many disadvantaged students often live. With this fact in mind, the study sought to evaluate national achievement efforts for these organizations and provide useful guidance to other CMOs, charter schools, and public schools around the country.
Public School Review's School Choice in 2026: What Parents Must Know provides additional context on how charter schools fit into today's expanding school-choice landscape.
This video examines the effectiveness of charter schools.
The Effectiveness of CMOs
The results of the Mathematica research were mixed, with the majority of CMOs studied providing positive effects with students and a few underachieving compared to other public schools in the area.
“CMOs are an important part of the education landscape and a subject of significant national attention,” Joshua Haimson, senior researcher for Mathematica, stated in the press release on the website. “Among the CMOs for which we were able to assess academic impact, many are having a strong positive effect, but some underperform relative to nearby public schools. Our findings on promising practices can inform efforts to improve school performance and substantially close school achievement gaps.”
Throughout the study, some relevant patterns were seen with the successful CMOs, including:
- CMOs typically have smaller schools than their public counterparts
- Classroom sizes were smaller on average than other schools
- CMOs offer additional instructional time through extended school days or shorter vacations
- CMOs are less likely to standardize curriculum for all of their schools
- These organizations tend to offer more intense coaching to teachers
- CMOs have a greater tendency to issue school-wide disciplinary policies
- These management organizations are more likely to pay teachers based on performance
These patterns could be used in the future for other CMOs, charter schools, and public schools to increase performance in these institutions as well.
Subsequent research has continued to find differences among charter operators. A national CMO study from CREDO at Stanford University found positive average academic effects across charter sectors in reading and positive mathematics effects for students attending CMO and hybrid schools, while also finding substantial variation among operators and school types.
Public School Review's How Schools are Governed and Funded provides additional background on the autonomy, governance, and accountability structures that distinguish charter schools from traditional public schools.
This video compares public schools with charter schools.
Results of the Study
In a nutshell, the Mathematica study found that of the 22 CMOs studied, 10 networks were outperforming nearby public schools in mathematics and reading. For the CMOs that were high-achieving, students were getting the equivalent of three years of instruction in just two years of class time. In addition, students that were considered high-achieving also outperformed their peers in subjects like science and social studies, suggesting that gains made in core curriculum areas were not made at the expense of other subjects.
The study also showed that some of the next eight CMOs studied also outperformed other neighboring schools, but not by much in this case. In fact, the data did not offer a statistically significant difference, leading to a possible conclusion that while these schools were on par with other public schools, they were not offering much additional benefit to the students who attended. A few of the schools in this group of eight were also behind other public schools in core subjects like math and reading, with a few showing a significant drop from the average seen in nearby public schools.
The final four CMOs examined in this study were shown to be seriously lagging behind other schools in their areas. In these underperforming schools, students were shown to be academically lagging behind others in their grades within two years of enrolling in the charter school. This led to some discussion among educators and academic experts on the need to become more efficient in closing charter schools that do not live up to expectations or standards relatively quickly.
That variation remains an important part of the charter school picture. Public School Review's New Report: Best (and Worst) Charter School Environments in America examines how state charter laws, oversight and accountability can affect the environments in which charter schools operate.
More recent national evidence offers a broader picture of charter performance. CREDO's 2023 national study examined approximately 1.8 million charter school students and found that, on average, charter students experienced stronger annual academic growth than comparable traditional public school students, equivalent to about 16 additional days of learning in reading and six additional days in mathematics. However, results varied by state, school type, and student population.
Public School Review's Charter Schools vs Public Schools 2025: Key Differences & Trends similarly notes that outcomes vary widely by individual school and network, with accountability measures remaining an important part of the charter model.
“We need to replicate what’s working within these high performers to ensure that all students can thrive in a high-quality public school,” Ursula Wright, then president and CEO of the National Alliance for Public Charter Schools, stated in a press release. “At the same time, we must also, as a movement, acknowledge that there is a small subset of CMOs that are not serving their students well. It is important that we take these results seriously and encourage charter authorizers, and the rest of the charter school community, to take steps to ensure that all public charter schools are meeting their intended promise.”
The central finding of the original Mathematica research therefore remains relevant in 2026: charter management organizations vary substantially in their effectiveness. More recent national research has found stronger average charter school performance, but differences among individual schools, networks and models continue to make quality and accountability important considerations for families, educators and charter authorizers.
