Charter schools: Finding out the facts


Since the early 1990s, the charter school concept has gained tremendous interest—and greater scrutiny—from the nation’s education leaders. While sometimes hailed as a model for raising student achievement, charters also are often misunderstood among the public at large. In fact, despite the unprecedented attention given to charter schools by President Obama and Education Secretary Arne Duncan, the majority of Americans have little understanding of and interaction with this growing sector of American education:

  • According to a survey conducted for the National Alliance for Public Charter Schools, only 41 percent of voters know that charters are actually public schools (NAPCS 2009c).
  • The National Charter School Research Project (NCSRP) reports that 89 percent of U.S. school districts “have no charter schools within their boundaries, perhaps in large measure because so many school districts are so very small" (Lake 2010).
  • Despite robust growth in some locations, charter school growth remains confined to certain states and the large cities within them.

In this report, the Center for Public Education provides a comprehensive look at charters to help school leaders make constructive decisions. Beginning with a detailed look at what a charter is—and what it is not—the document then summarizes the growing body of descriptive information about charters, including the types of organizations that sponsor them and the way state governments oversee their creation. In addition, we examine the slim but growing research base to determine whether charter schools are working and, if so, what lessons public education can take from them. From the available research, it seems that the attention paid to charter schools outweighs the effect they have had on public education, either good or bad.

What is a charter school?

Simply put, a charter school is a non-religious, public school operating under a contract, or “charter,” that governs its operation. For almost two decades, charter schools have evolved as a way to experiment with education innovations and provide public school choice. All details of school operation —its name, organization, management, and curriculum—are set by the charter, which also outlines how the school will measure student performance.

Charter schools are similar to traditional public schools in that they are publicly funded, and their students must participate in statewide testing programs. Charter schools must submit to the Adequate Yearly Progress review under No Child Left Behind, and they are subject to federal accountability guidelines if they receive Title I funds. Also, charter schools must have open enrollment policies and cannot discriminate based on academic ability, disability, race, color, gender, national origin, religion, or ancestry. They cannot charge tuition.

One of the key differences between charter schools and traditional public schools is their regulatory freedom and autonomy (in terms of staffing, curriculum choices, and budget management), which they receive in exchange for their charters being reviewed and renewed or revoked by the authorizing agency.

The process is driven primarily by state law. Minnesota passed the first charter school law in 1991, followed soon thereafter by California in 1992. By 2003, the vast majority of states had enacted charter school legislation. Nonetheless, current state interest in the issue is arguably at its highest level because of recent decisions by the Obama White House. The administration has made charters a focal point under its Race to the Top program with competitive dollars for education improvement, an effort that is prompting many states to re-examine their policies (see sidebar).

Among the thirty-nine states* with charter school laws, rules vary widely on funding, operational requirements, and accountability. As a result, charter school organizers often must meet multiple state and local requirements. For school board members, one paramount issue is how each state decides how to approve new charter schools. Data from the National Alliance for Public Charter Schools (2010) illustrate the varied approaches:

  • In seven states chartering authority rests solely with local school boards
  • In three states the state education agency is solely responsible
  • In seven states authority rests with the local school district and the state education agency
  • In three states the local school board must approve a charter first, and then it must be approved by the state board of education
  • In the District of Columbia and Hawaii (which are single school district jurisdictions) the state charter board alone makes decisions
  • In four states authority falls to the local school district and a state charter board
  • In 14 states authority rests with a combination of the above agencies and, in some cases, a higher education institution or non-profit organization.

Table 1: Public charter school authorizers, 2009–2010

Local school board alone IL, MD, OR, PA, TN, VA, WY 
State board of education alone CT, MA, NJ
Local school board and
State board of education
First Local school board then
State board of education
State charter school review board D.C., HI
Local school board and 
State charter school commission
Combination (in some cases including higher
education and not-for-profit)

Source: National Alliance for Public Charter Schools, State Charter Law Rankings Database, 2010
*Mississippi's charter law expired at the end of 2009, bringing the total to eleven states without charter school legislation: AL, KY, ME, MS, MT, NE ND, SD, VT, WA, WV

As a result of these varied authorizing arrangements, an organization seeking to open a charter school must navigate a range of operational and bureaucratic requirements.

Yet charters may have many distinct differences from traditional public schools:

  • They are governed by their charters, whose terms vary. Most are granted for three to five years, and these charters must be reviewed and renewed  
    Race to the top

    The status of some states’ charter school legislation is in flux as state leaders consider changes to boost their chances of receiving support under the U. S. Department of Education’s Race to the Top Fund. Part of the American Recovery and Reinvestment Act, commonly known as the eco-nomic stimulus law of 2009, Race to the Top will allocate $4.35 billion in competitive grants to state education agencies in 2010. State support for charter schools can account for 40 points (of a possible 500) in the overall application competition. The government will measure “state support” by criteria such as the existence of charter legislation, comparisons of per-pupil funding at charter and traditional public schools and whether the state encourages the growth of charter schools by removing caps or allowing a high percentage of charter schools. Grants to individual states can range from $20 million to $700 million, depending on the state’s overall public school enrollment.

    You can find more information at

    by the authorizing agency.

  • They have autonomy from many state and district regulations—including, in some cases, collective bargaining rights for teachers. As a result of these factors, charters may have more control over hiring and firing decisions and salary determinations.
  • The schools also can determine their own budgets, class and school size, and the length of the school day and year.
  • Charter schools are likely to be smaller and more concentrated in urban areas than traditional public schools, largely due to a desire for more options for a child’s education.

Finally, enrollment in charter schools is small, but growing. While charter school students enrolled just 3 percent of all public school students in 2008, the number of students (and schools) has risen dramatically in the past decade.  In 1999, there were 1,542 charter schools with 349,642 students. By 2008, there were 4,618 charter schools with 1,407,817 students (National Alliance for Public Charter Schools 2009b). For detailed state-by-state data see Table 2.

Frederick Hess, education policy director at the American Enterprise Institute and a strong advocate for charter schools, notes that many charter sponsors rely on dedicated staff and a “missionary zeal” to succeed (Hess 2009). “The most successful charter ventures to date have been boutique-style operations that are extraordinarily reliant on talent and passion, philanthropic funding, and exhausting work schedules,” (Higgins and Hess 2009). Yet, he notes, the “means of bringing them to scale have been elusive.”

Table 3: Comparison of traditional public schools and charter schools

  Traditional public schools Charter schools
Accountability Must measure adequate yearly
progress (AYP)
Must measure adequate yearly
progress (AYP)
No. of schools and
enrollment (2008-2009)
90,624 schools with
47,627,752 students
4,618 schools with
1,407,817 students
Distribution of schools    
By location (2006-2007)
24.7 percent
28.2 percent 
14.9 percent
32.2 percent
53.7 percent
21.9 percent
8.7 percent
15.6 percent
By level (2003-2004)
70.2 percent
22.5 percent
7.2 percent
52.9 percent
23.9 percent
23.2 percent
By size (2003-2004)
Less than 300 students
300–599 students
600–999 students
1,000 or more students
28.2 percent
39.2 percent
21.9 percent
10.5 percent
67.9 percent
19.2 percent
9.9 percent
3 percent
Funding levels
Per pupil revenues (2002-2003)
$8,504 $6,704

Sources: Public Charter School Dashboard, 2009; 2008 NCES Digest of Education Statistics, Schools, and Staffing Survey Table Generator. Revenues data come from Finn, Hassel, and Speakman (2005), based on 16 states and D.C.

Role of management organizations

One major factor driving the development and growth of charter schools is the role of educational management organizations, or EMOs. Today EMOs run almost 30 percent of all charter schools.

Charter schools and funding

It is important to note that while charter schools receive most of their funds from states, the federal government offers some funding through a competitive grants program. The U.S. Education Department’s Charter Schools Program grew steadily in the first part of the decade, moving from $145 million in 2000 to $218 million by 2004. It remained flat until recently, receiving $216 million from Congress for fiscal year 2009, when it received $256 million for fiscal year 2010. President Obama also proposed in his fiscal year 2011 budget to consolidate several initiatives into one program for expanding educational options, including charter schools, for $490 million. 

If a state chooses not to participate or does not receive funding because it does not have a charter school law, the federal government can provide grants directly to charter school operators.  Funding from Race to the Top (see box) or from school improvement grants can also be used for creating or expanding high-performing charter schools, as one of the school improvement intervention models school districts can choose to implement. 

State policies on financing charter schools are of significant interest, yet few studies have addressed this issue. Researchers at Fordham Institute, one of the few active in this area, have noted the difficulty in trying to collect such data.  Finn, Hassel, and Speakman (2005) stated, “This analysis revealed beyond our wildest fears how uneven, incommensurable, and in many cases plain shoddy and gap-filled are state and local school-finance data. It’s hard enough to figure out how much money flows into the coffers of district-operated schools in a given year, whence it comes, and what formulas govern the amount and shape the channels through which it flows. To find these things out for charter schools in any fashion that can begin to be compared with district (or state) data verges on impossible.” Studies that determine relationships between charter school finance policies and academic achievement would be useful.

EMOs began in the 1990s, largely as for-profit entities, thereby interjecting entrepreneurship into public schools. Initially, most for-profit EMOs simply took over management of existing public schools, primarily in urban areas. Today, however, such organizations also are active in charter school operation and management. For-profit EMOs run about 16 percent of all charter schools.

In addition, as the charter school movement has spread, many non-profit organizations have begun to operate and manage multiple charter schools—often across different states. Some researchers have dubbed these entities “charter management organizations” while others, including this report, use the term non-profit EMOs. Non-profit EMOs run about 13 percent of all charter schools.

Regardless of profit status, one reason for the existence of EMOs is their ability to use economies of scale to address infrastructure and operational issues facing charter schools. In addition, by maintaining a central home office, these EMOs can centralize many administrative duties. Also, medium- and large EMOs can receive a level of state funding unavailable to so-called “mom-and-pop” charters. 

Non-profit EMOs

During the 2008–2009 school year, one hundred three non-profit EMOs managed six hundred nine public charter schools across twenty-fivestates (Miron and Urschel 2009a). The number of non-profit EMOs has increased substantially in recent years; back in 1995, only five of these non-profits operated charters. Also, while the growth rate is slowing for for-profit EMOs, the number of non-profits continues to grow steadily. Non-profit EMOs are most prevalent in Texas, California, Arizona, and Ohio.

An organization with more than 10 charters is considered by Miron and Urschel (2009a and 2009b) to be a large EMO. Of these, KIPP Academies is the largest, with 64 schools in 2008-’09. The researchers identified 16 “large” EMOs nationwide, along with 40 small EMOs and 47 medium-sized organizations. The chart below shows the largest for-profit and non-profit EMOs nationwide, which together run approximately 10 percent of all charter schools, enrolling 209,519 students. 

For-profit EMOs

For-profit educational management organizations are growing at a slow rate (Miron and Urschel 2009b). Overall, ninety-five for-profit EMOs were in existence in 2008–2009, up from fourteen during the 1997–1998 school year. For-profits managed seven hundred thirty-three schools last year. Michigan and Florida had the largest number with one hundred ninety-one and one hundred thirty-six, respectively. As recently as 2000, for-profit EMOs managed charters and regular public schools in somewhat similar numbers. However, that ratio has changed dramatically during this decade. By 2008–2009, charters represented 94 percent of the schools managed by for-profit organizations.

Table 4: Largest education management organizations, 2008–2009

Name Headquarters Status # of Schools Enrollment States
Imagine Schools
Arlington, VA For profit 76 32,316 10: AZ, DC, FL,GA, IN, MD, MI, MO, NV, OH
Leona Group
Phoeix, AZ    For profit 67 18,577 6: AZ, FL, IN, LA, MI, OH
KIPP San Francisco,
Non profit 64 17,211 20: AR, CA, CO, DC, GA, IL, IN, LA, MA, MD, MN, MO, NC, NJ, NY, OH, OK, PA, TN, TX
National Heritage
Grand Rapids, MI For profit 57 36,737 6: CO, IN, MI, NC, NY, OH
Academica Miami, FL For profit 54 20,105 3: FL, TX, UT
White Hat
Akron, OH For profit 51 16,326 6: AZ, CO, FL, MI, OH, PA
Education, Inc.
New York, NY For profit 33 10,163 8: AZ, CO, DC, IL, IN, MI, OH, PA
Edison Learning New York, NY For profit 31 19,654 12: CA, CO, GA, IL, LA, MI, MN, MO, NY, OH, PA, WI
Summit Academy
Copley, OH Non profit 26 1,914 1: OH

K12, Inc. *

*runs virtual charter

Herndon, VA For profit 22 36,516 13: AR, AZ, CA, CO, ID, IL, IN, NV, OH, PA, SC, TX, WI
    481 209,519  

Source: Miron, G. and Urschel, J. (2009a and 2009 ). Profiles of nonprofit education management organizations: 2008–2009.
Note: NAPCS makes a distinction between nonprofit EMOs, which they call Charter Management Organizations, and for profit, Education Management Organizations. CMOs tend to be smaller than EMOs (notice there are only two of them on the list above) and one of the other best-known nonprofit EMOs is Green Dot, which only had 15 schools enrolling 5,622 students in Los Angeles, CA in the 2008–2009 school year.

The newest trend: Going virtual

For school board leaders just learning about charter schools, there’s another trend to consider: The virtual charter. EMOs are creating a growing number of virtual or cyber charter schools, which deliver curriculum and provide instruction via the Internet and electronic communication.* 
*(Note: The best source for information on this sector is the Education and the Public Interest Center’s reports on EMOs; the Center first started tracking virtual schools in 2003–2004. See Molnar, Wilson, and Allen, 2004 and Miron and Urschel 2009b.)

For-profit EMOs have increased the number of virtual charter schools they operate from thirteen in the 2003–2004 school year to fifty by 2008–2009. Nonprofit EMOs do not appear to be as interested in virtual charters, with only four schools in 2008–2009 (Miron and Urschel 2009a). Geographically, virtual charters appear to be concentrated in a handful of states, including Arizona, California, and Ohio.

There is little research on virtual charters, or on how the model of a charter school works with the instructional differences as well as the funding requirements inherent in online learning. A recent review of research (Cavanaugh 2009) indicated “mixed outcomes” when comparing virtual charter school achievement with classroom-based charter programs. Cavanaugh found that twelve studies show no statistical difference between students in both categories and two studies found lower test scores for virtual charter students. A RAND Corporation study also voiced concerns about the growth of these schools, noting that in Ohio, virtual charter school students’ achievement gains in math and reading “fell significantly short of those in traditional public schools and classroom-based charter schools” (Zimmer et al 2009). Both Cavanaugh (2009) and the RAND authors (Zimmer et al 2009) call for additional research on virtual charters, stating that little is known about the population of virtual charter students. Other interesting trends include:

  • Virtual charter schools can have larger enrollments than classroom-based charter schools. For example, nonprofit Buckeye On-line School for Success in East Liverpool, OH has a K–12 enrollment of 1,783 students.
  • Most of the virtual charter schools are K–12, but some have unusual grade arrangements such as 10–12 or 7–12.
  • Arizona, California, and Ohio appear to have the largest number of virtual charter schools. However, the trend is so new that existing data sources may be incomplete or may include any type of virtual school (including non-charters).

Also, according to Miron and Urschel (2009b), the bulk of virtual charter schools were run by three large EMOs in 2008–2009:

  1. Connections Academy’s with eleven charters and total enrollment of 11,598 in ten states
  2. K12 Inc. has twenty-two schools with a total enrollment of 36,516 in thirteen states
  3. Insight Schools manages ten virtual charter schools across nine states with a total enrollment of 4,548 students

Unfinished business: The nature and quality of charter school research

As the number of charter schools has grown nationwide, so too has the research base. However, despite some progress, rigorous research in this field remains in its infancy. While there are literally hundreds of studies on charters, a high proportion of these studies can be categorized as less rigorous “snapshot” studies. Given the “young age” of most charter schools, a high proportion of these studies provide only a one-time analysis of student data and other characteristics of charter schools. Many also focus on a small number of schools in one district or one city. Most importantly, since charters (and the rules governing them) vary so greatly from state to state, it is difficult to reliably evaluate them. As interest in the field has grown, more researchers are proposing broad, in-depth studies that collect longitudinal student-level data with rigorous research methods to evaluate the impact of charter school attendance across multiple sites and states.

Two recent meta-analyses have examined the existing research on charter schools: The National Alliance for Public Charter Schools (NAPCS) (2009a) and Betts and Tang (2008). The NAPCS report documented two hundred ten charter school achievement studies, but rejected seventy outright since they did not meet what they deemed their minimal criteria:

  • The study must compare charter school achievement with that of traditional public schools
  • The study must use serious research methods
  • The study examines a significant segment of the charter sector

The Alliance differentiates between three types of studies: Panel studies, which use student-level, longitudinal data to compare charter students with similar students at traditional public schools; cohort change studies, which typically examine averages of school-wide test scores; and
snapshot studies that analyze achievement at one point in time.

NAPCS has identified panel studies as “the gold standard” for examining comprehensive student-level data and controlling for prior achievement and other characteristics. Nonetheless, the group acknowledges these are the most expensive and difficult to conduct. Moreover, the Alliance meta-analysis ultimately included just nineteen of the thirty-three panel studies, since fourteen rely on older data prior to the 2001–2002 school year.

Betts and Tang (2008) were even more stringent in analyzing charter school studies. They identified only thirteen studies that had a high quality design and collected enough data to calculate effect sizes. This meta-analysis focused on identifying studies that included randomization based on lotteries and/or considered a student’s past achievement.

Most studies offer snapshots, not evaluations. Both meta-analyses noted that most charter school research falls into the “snapshot” category because these are the easiest and least expensive to do. Betts and Tang (2008) rejected such studies for their meta-analysis, cautioning that such studies do not “take into account the relatively disadvantaged backgrounds of students who attend charter schools” and therefore, may not present an accurate picture of the schools’ impact on academic achievement.

Studies are clustered in a few states. NAPCS (2009a) noted that charter school students in eleven states have not been included in any major studies, other than those reviewing national data such as National Assessment of Educational Progress (NAEP) scores. In seven other states, only snapshot studies provide a glimpse of the impact of charter schools. The Alliance is particularly concerned that some states with large numbers of charter students (Michigan, Minnesota, and New Jersey) do not have a single longitudinal, student-level study published, and charter students in some of the states with significant recent growth in charter schools (Georgia, Louisiana, and South Carolina) have not received rigorous study at all.

Many studies focus on schools in a specific city or district, or a specific model or charter provider (such as KIPP). NAPCS (2009a) found that seventeen of the panel studies, seventeen of the cohort change studies, and twenty of the snapshot studies were focused on a particular city or school district. Also, the Knowledge is Power Program (KIPP), a national charter school network, is one of the most studied charter models.

Few studies examine charter schools across states. Again due the difficulty in analyzing charter schools, most studies are not able to collect and analyze data in more than one state. Two recent studies have added a great deal to the knowledge of charter schools’ impact by focusing on several states: A 2009 study by the Center for Research on Education Outcomes (CREDO) that examines the performance of charter schools compared to traditional public schools across fifteen states and the District of Columbia— fully 70 percent of national enrollment in charter schools—and a long-term study from the RAND Corporation that analyzes results including high school graduation rates and college enrollment rates for charter students in eight states (Zimmer, Gill, Booker, Lavertu, Sass, and Witte 2009; Booker, Sass, Gill, and Zimmer 2008).

A sizable portion of the research tends to be descriptive in nature, looking at the number of schools and students and describing charter legislation. While this information can be useful for policymakers, including school board members, the map of charters is ever-changing, and there are many reports that simply offer statistics.

What do we know about charter school effectiveness?

For educators and school board members, one fundamental question is whether charter school students perform better than students in traditional public schools. Unfortunately, even with the hundreds of studies on charter schools, the answer appears to be, “It depends.”  Some studies show impressive gains in reading and math and, in some cases, improved high school graduation and college enrollment rates. Yet other studies show charter school students underperforming compared with their peers in traditional public schools. Perhaps this is not surprising, as charter schools can look quite different from state to state and even city to city or district to district.   The following sections provide more information about these trends based on recent research. 

Assessments in math and reading

In one of Betts and Tang’s (2008) major conclusions, a majority of the studies showed that charter schools performed better than traditional public school students in elementary school reading and middle school math. (Overall trends in elementary school math and middle school reading were inconclusive.) Conversely, charter schools underperform in these areas at the high school level. As noted earlier, this meta-analysis was stringent in reviewing charter school research, identifying only thirteen studies as possessing a high-quality design. Similar results were found in a more recent study (2009) from CREDO, which analyzed reading and math scores from charter students in fifteen states and the District of Columbia and compared them to “virtual twins” based on student demographics, English language proficiency and participation in special education or subsidized lunch programs. Where gains were evident, CREDO found, the success was generally in reading at the elementary level and in reading and math at the middle school level. (There was no difference in elementary school math.) Despite these generally positive findings, the study found no evidence of a net gain during high school. In addition, students in “multi-level” (i.e., K–8 or 7–12) charter schools underperformed counterparts from traditional public schools in both reading and math.

Table 5: Average charter school performance relative to traditional public
schools by state

  Reading Math
Arizona Lower Lower
Arkansas Higher Higher
Colorado Higher Higher
California Higher Lower
DC No Difference No Difference
Florida Lower Lower
Georgia No Difference Lower
Illinois No Difference Higher
Louisiana Higher Higher
Minnesota Lower Lower
Missouri Higher Higher
North Carolina Higher Lower
New Mexico Lower Lower
Ohio No Difference Lower
Texas Lower Lower

Source: CREDO (2009)

CREDO also moved beyond individual subjects to examine the overall performance of the school in math and reading. They found that while some charter schools do better than traditional public schools, the majority do the same or worse. Almost one-fifth of charters (17 percent) performed significantly better (at the 95 percent confidence level) than the traditional public school. However, an even larger group of charters (37 percent) performed significantly worse in terms of reading and math. The remainder (46 percent) did not do significantly better or worse.

Figure 1           

Similar to other studies, CREDO found varied performance results based on students’ location. In relation to their peers in traditional schools, the average performance of charter school students in reading was significantly positive in Arkansas, California, Colorado (Denver), Louisiana, Missouri, and North Carolina. In the District of Columbia, Georgia, Illinois (Chicago) and Ohio, there essentially was no difference between charter students and their traditional public school peers. In Arizona, Florida, Minnesota, New Mexico and Texas, charter school students underperformed when compared with students in traditional public schools.

The math data were similarly varied. Charter students did better than their counterparts in Arkansas, Colorado (Denver), Illinois (Chicago), Louisiana, and Missouri. There was no significant difference in the District of Columbia. In Arizona, California, Florida, Georgia, Minnesota, New Mexico, North Carolina, Ohio and Texas, charter school students did not perform as well as their virtual twins from traditional public schools.

Other academic indicators

In addition to math and reading assessments, some studies have looked at other indicators such as ACT scores, high school graduation rates, and college enrollment rates. The RAND Corporation (Zimmer et al 2009; Booker, Sass, Gill, and Zimmer 2008) analyzed various indicators for charter students in eight states and collected data on specific long-term outcomes for charter students in Chicago and Florida. Findings from this longitudinal study indicate that students attending charter high schools have higher ACT scores and are more likely to graduate from high school and attend college than students who attend traditional public high schools.   For example, the study found charter high school students were more likely (by 8 to 10 percentage points) to enroll in college than were their traditional public school counterparts.

Nonetheless, RAND researchers found little evidence that charter school students had higher test scores in high school than those in traditional public schools. As a result, they recommended additional research, in effect acknowledging they were surprised by some of the graduation and college enrollment findings. The researchers wrote, “Our estimates of positive charter-school effects of high-school graduation and college entry are more encouraging than most of the test score-based studies to date (including our own test-score results).” They continued, “Nevertheless, our positive results are promising and are not fully explained by estimated impacts on test scores, suggesting that researchers and policymakers need to look beyond test scores to fully assess charter schools’ performance.”

It should be noted that the RAND study collected data from some sites that were not included in either the CREDO or Betts and Tang studies. In addition, CREDO focused on math and reading achievement while RAND also emphasized longer-term outcomes such as high school graduation or college enrollment. One possible explanation for the difference between standardized test scores and positive high school and college outcomes may be the motivation of students and their families. Although RAND controlled for student demographics they were not able to control for unobservable characteristics like student motivation. It is not unreasonable to suggest that students and/or families that take the time to seek out charter schools—often out of their immediate neighborhoods—may have high academic expectations and, hence, a stronger commitment to having a child attend college.

Policy impacts

Since school board members may want a voice in charter school decisions within their communities, it is important to determine if correlations exist between charter school achievement outcomes and various state policies regarding charter schools. Specifically, does participation by a local school district or state agency in charter authorization lead to better or worse charter schools? Again, the answers are far from clear. However, there are some data available for examination.

Governance and multiple authorizers

As noted previously, school board and district involvement in charters is uneven nationwide. 
Although school districts are the major authorizers of charter schools, according to the National Charter School Research Project (Lake and Hill 2006), “Only 8 percent of the almost 9,000 school districts with authority to charter schools” had done so by 2006. Yet while local policies are a factor, state law drives many of these decisions. While only seven states give school districts sole authority to create charters, fourteen give districts a substantial role along with a state agency such as the Board of Education or an independent charter board. Fourteen expressly allow multiple authorizers, which can include school districts among a large, diverse set of players that include state agencies, colleges and universities, municipal government agencie, and other non-profit organizations.

The CREDO study addressed this issue in some detail, and it is noteworthy to compare CREDO’s state-by-state findings with NAPCS data on public school authorizers. Unfortunately, the CREDO study did not include a state in which local school districts/boards were the sole authorizers of charter schools. Nonetheless, it was clear on one point: States that allow multiple authorizers—from municipal agencies to colleges and non-profits—had the weakest student achievement data for charter students when compared to students at traditional public schools. CREDO found “a significant negative impact on student academic growth” for charters in states that allow multiple agencies to authorize these schools. In effect, CREDO said, the presence of multiple authorizers allows charter organizers to “shop” for the most advantageous route to approval. The finding on achievement “suggests that applicants are strategic in their choice of authorizer and look for the option that is ‘easiest’ on charters,” CREDO concluded.

Looking at state data in reading and math, CREDO says, charter students fared worse than their non-charter counterparts in Arizona, Florida, Minnesota, and Texas. In addition, students in Ohio scored worse in math and showed no difference compared to traditional public school students in reading. Among these five states, four allow multiple authorizers, with a less prominent role for local school districts. In Florida, colleges and universities and an independent charter board are among groups that may authorize charter schools. In Minnesota and Ohio, colleges and universities and non-profit organizations join local schools on the list of charter authorizing agencies.

Who are charter authorizers?

Created in 2000, the National Association of Charter School Authorizers (NACSA) has a multi-year effort underway to collect data on authorizers. So far, it has identified more than 800 active authorizers of charter schools—the vast majority of whom are local school districts (NACSA, 2009). Yet most administer fewer than five charters.

One rich data set available is on the top 50 authorizers ranked by number of charter schools. Of this group, 21 are local school districts. These 50 play a significant role: They are responsible for 2,349 charter schools and 855,000 students—61 percent of all those attending charters nationwide. The largest authorizer is the Arizona Board of Charter Schools with 366 schools. From 2005 to 2008, the top 50 authorizers:

  • Received more than 1,400 applications for new schools, granting charters to 516 (34 percent);
  • Received 694 renewal applications from existing charters, granting 87 percent of renewal petitions;
  • Revoked charters for 44 schools prior to the charter term’s contracted end date.

Similarly, the RAND Corporation (Zimmer et al 2009), in analyzing eight states, found that Ohio had “an especially wide range of variation” in achievement, which the authors attributed to the state’s “unusually diverse group of organizations to serve as charter authorizers.”  The CREDO authors reached the same conclusion, suggesting, “It appears that charter school operators are able to identify and choose the more permissive entity to provide them oversight.”

While these findings may be too limited to draw national conclusions, they do demonstrate the need for additional research on another under-researched issue in charter schools: The importance of charter school authorizers (see sidebar).

State caps and appeals

The CREDO study is the only large-scale study of charter schools that has tried to analyze the correlation between certain state policies and students’ academic performance. One particular state policy drawing CREDO attention is the effect of caps—when states set limits on the number of charters they allow. Study authors concluded that, “States that have limits on the number of charter schools permitted to operate, known as caps, realize significantly lower academic growth than states without caps,”  in terms of charter school performance. The study even predicts that when a state removes its cap, charter schools in that state “can expect a gain in academic achievement.” This conclusion seems to contradict some of the study’s other findings about which states’ charter schools had higher or lower than expected learning gains. For example, Arkansas, Illinois, and Missouri had higher academic gains for charter students than traditional public school students, yet these states have a cap on the number of charters. Also, charters’ learning gains in Arizona, Florida, and Minnesota (states that have no charter caps) were lower than those of traditional public schools.

The issue of charter school caps is likely to gain additional attention in coming years, since states have been encouraged to lift or eliminate their caps to be more competitive when seeking funds under the U.S. Education Department’s Race to the Top grant program. With these recent changes in state charter legislation, more research is needed to see if there is a relationship between caps and academic achievement or if other factors are involved.

For both caps and multiple authorizers, it is good to remember that correlation is not causation; more research should be done to see if there is a relationship or if other factors are involved.

Some states also have an appeals process, through which prospective charter operators can contest the denial of a charter. CREDO suggests that an appeals process may have a positive effect on quality. States with an appeals process have slightly better charter school student performance than states without such an option. One possible explanation may be that the appeals process adds “additional scrutiny” to decisions at the authorizer level, which in the long run improves quality.

Impact on different student groups

Table 6: Student racial/ethnic composition of charter schools and traditional
public schools, 2008–2009

  Traditional Public Schools Charter Schools
White 53.4 percent 38.4 percent
Black 16.8 percent 29.7 percent
Hispanic 22.1 percent 24.7 percent
Asian American 4.9 percent 3.9 percent
Other 2.8 percent 3.3 percent

Note: Since charter schools are more likely to operate in urban areas, it is not surprising that they have smaller proportions of white students and larger proportions of black and Hispanic students.

The RAND Corporation’s study (Zimmer et al 2009) attempted to evaluate whether charter schools are “skimming” the best students from local traditional public schools or resegregating urban schools. RAND analyzed the academic achievement and demographic characteristics of students transferring into charter schools and found that:

  • Charter schools generally are not drawing the best students away from local traditional public schools. For example, previous test scores for students transferring into charter schools were near or below the averages for every location in the study. Only among white students did researchers find slightly higher test scores for those moving to charter schools.
  • The racial composition of charter schools was similar to that of the traditional public schools the students previously attended.* 
    *Note: While this finding appears to contradict table 9, this is probably due to the higher proportion of rural schools in the traditional public schools category, which are typically less diverse.

A recent report by the Civil Rights Project compared the percent of black students in racially isolated charter schools (charters schools enrolling 90 to 100 percent of black students) to the percent of black students attending racially isolated school nationwide, with the conclusion that black charter school students are twice as likely to attend racially isolated schools. However, the majority of charter schools are in large urban districts, which are more racially isolated than other districts. So it cannot be determined from the CRP report whether charter schools lead to more racially isolated schools; the RAND study remains the best research available.

It’s important to look at not just the overall achievement of charter school students, but the performance of specific student subgroups, because these subgroups’ performance often differs from the average. However, few multi-site or multi-state studies examine how specific racial/ethnic groups perform in charter schools, and those that exist often show conflicting results. A summary of key findings:

Black and Hispanic students –The RAND study (Zimmer et al 2009) compared math and reading achievement outcomes of black, Hispanic and white students in nonprimary charter schools, and most of the findings were not statistically significant (sites were Chicago, Denver, Milwaukee, Philadelphia, San Diego, and the states of Ohio and Texas). The CREDO report is another example of these mixed results. Generally, math and reading gains for black and Hispanic students in charter schools were smaller than the gains for their counterparts in traditional public schools, yet these results varied widely by state.  Black charter students fared better in both math and reading in Louisiana, Minnesota, and Missouri, yet in Florida, Georgia and Texas, they fared worse than their counterparts in traditional public schools. In addition, African Americans in charter schools had positive reading gains in California and math gains in Arkansas but showed reading losses in Illinois and math losses in Arizona and North Carolina.

For Hispanic charter school students, only Missouri posted positive gains in both reading and math, CREDO says.  In Arizona, Colorado, and Louisiana, Hispanic charter students had positive math gains relative to their virtual traditional school twins.  Georgia, Illinois, New Mexico and Ohio charter schools had negative results for Hispanic students in both reading and math, and Hispanic charter students fared poorly in reading in Texas and in math in Arizona and California.

A recent report (Braun, Jenkins and Grigg 2006) from the National Center for Education Statistics analyzed data for the National Assessment of Educational Progress (NAEP) based on an oversample of charter schools.  While the study did not look specifically at Hispanic and black performance, it compared traditional and charter schools with high minority enrollments (defined as 50 percent or more black and Hispanic students) to all other public schools. Interestingly, this study found that while the math and reading performance on NAEP was not statistically different between high minority charter schools and other charter schools, or between at high minority charter schools and typical high-minority public schools, high minority traditional public schools.

English language learners – CREDO (2009) found that, based on aggregate data from all the states, charter students who are English language learners outperformed their peers in traditional public schools in both reading and math. However, when looking at individual states, the data was only strong enough to be significant in five states (California, Arizona, New Mexico, Texas, and Georgia), and one state showed a negative effect (Missouri).  

Low-income students – Typically identified through participation in subsidized lunch programs, low-income students attending charter schools are performing better than their traditional school peers in both math and reading, according to the CREDO (2009) study, especially in Arkansas, California, Georgia, Illinois, Ohio, and Texas. NACPS (2009b) found that 36 percent of charter school students are eligible for free or reduced price lunch, compared with 46 percent of non-charter public school students.

Special education students – CREDO found that special education students in charter schools fared the same as counterparts in traditional public schools, with the exception of those special education students in Arizona and California charter schools, who outperformed their peers.

It should be noted that many small studies have examined impacts of charter schools on specific subgroups. However, for the purposes of this section, the center is including only those studies that include multiple states and have been identified as rigorous by charter school scholars.

Teachers at charter schools

Consistent with the theme that charters look different than traditional public schools, it may be no surprise that charter teachers also bear some noteworthy differences. Based on available data, charter school staffs appear more diverse, have fewer years of experience, and are paid less than those at the typical public school. The 2003–2004 Schools and Staffing Survey of the National Center for Education Statistics shows teachers at public charters are more likely to be black, Hispanic, Asian American or Native American than their counterparts at traditional public schools (see table). No one has examined, however, whether some of this might be due to charter schools often being located in urban areas. The survey also shows charter teachers have less experience than those at typical public schools; more than one-fourth (29 percent) had less than three years full-time teaching experience compared with 12 percent of those at traditional schools.

Caroline Hoxby’s (2002) research surveying private, traditional public and charter public school teachers found that, on average, charter schools paid less than traditional public schools but higher than private schools. While the average public school teacher earned $34,690, the typical charter school teacher was slightly behind at $32,070, or by about 8 percent. Nonetheless, the charter school salary was far above the $21,286 typically paid to private school teachers.

However, charters were more likely than traditional public schools to have differential pay levels. Hoxby’s survey showed that charter schools were willing to pay more for teachers with degrees from select colleges, with degrees in a subject (such as history or English) as opposed to education, those with strong math / science skills, and those willing to work extra hours beyond the regular school day. For example, traditional public school teachers who graduated from very competitive colleges were paid 3.1 percent more than their peers, while charter school teachers from the same group of colleges are paid 6.6 percent more than their colleagues.

Future research might examine if the comparison of average charter school teacher salary accounted for charter school teachers’ years of experience, or by the longer hours worked by some teachers.

As independently operating public schools, many charters are exempt from typical hiring and dismissal regulations, including those for collective bargaining. This issue has generated much debate, as some scholars argue that this flexibility is essential to cutting bureaucratic requirements and promoting success. Yet others—including teacher unions—say charter teachers often need greater protections due to their demanding jobs. The American Federation of Teachers’ arm in New York City actively works with charter school teachers, and one charter organization—Green Dot Schools—touts its credentials as “the only non-district public school operator in California that has unionized teachers” (Green Dot Public Schools 2010).
In a recent article, the Harvard Education Letter attempted to put an estimate on the number of unionized charters (Russo 2010). From nearly 5,000 charters nationwide:

  • The American Federation of Teachers claims to have organized 80 schools;
  • The National Education Association says it is “working with” about 200 charters;
  • The National Alliance of Public Charter Schools says the number of unionized charters is “somewhere below 500.”

At the same time, philanthropies are taking an interest in the charter/union issue. According to Russo, the Eli and Edythe Broad Foundation and The Joyce Foundation are touting model charter contracts—some have dubbed them ‘Thin Contracts’—that might apply to individual charters or small groups of schools. Nonetheless, while the issue draws debate, it affects rela-tively few schools now. As the National Charter School Research Project’s 2009 annual report states, “Given these relatively small numbers, it is hard to call charter unionization a trend” (Lake 2010).

Table 7: Teaching Staff at Traditional Public Schools and Charter Public
Schools, 2003–2004

Racial/Ethnic Composition     Years of


  Traditional Public Schools Charter Public Schools     Traditional Public Schools Charter Public Schools
White 84.5 percent 71.1 percent   Less than 3 years 12 percent 29.3 percent
Black 8.2 percent 16.4 percent   3 to 9 years 32.8 percent 48.4 percent
Hispanic 5.7 percent 8.8 percent   10 to 20 years 28.8 percent 14.5 percent
Asian American 1.3 percent 2.6 percent   20 or more years 26.4 percent 7.7 percent
American Indian 0.4 percent 1.2 percent        

Source: National Center for Education Statistics. (2009) Digest of Education Statistics, 2008 (NCES 2009-020).
Based on available data, charter school staffs appear more diverse and have fewer years of experience, but since over half of charter schools are in urban areas, more research needs to be done to see if that affects staff composition.

Unanswered questions

Despite the growth of charters, organizations such as the National Alliance for Public Charter Schools and others note a paucity of rigorous research on the phenomenon, with much work left to be done. According to NAPCS (2009a), the charter school experience has been studied via comprehensive panel studies in less than half of the states with existing charters. In addition, charter school students in eleven states have not been included in any studies other than those reviewing national data such as NAEP scores. In another seven states, only snapshot studies provide a limited glimpse of charter school impact. The Alliance is particularly concerned that some states with large numbers of charter students (Michigan, Minnesota, and New Jersey) do not have a single longitudinal, student-level study published, and charter students in some states with significant recent growth in charters (Georgia, Louisiana, and South Carolina) have not had studies at all.

Betts and Tang (2008) also cite the need for studies of charter high schools, noting that their own conclusions about how charters are underperforming in math and reading at the high school level are based only on a small number of studies on schools in Texas, Idaho, Delaware, plus some large urban districts in California. Clearly there is a need for additional rigorous research on charters to inform the current debate over their effectiveness.

In addition, another oft-mentioned goal of the charter movement is that it should generate new ideas and innovation in neighboring traditional public schools. Few studies have examined this issue. One study (Teske, Schneider, and Buckley, and Clark 2000) analyzed traditional public schools and charters in districts in Massachusetts, New Jersey, and Washington, D.C., and found “little evidence of shared ideas and information.” The authors hypothesized that this was due to a lack of communication and, in some cases, hostility between the two sectors. However, as this paper is a decade old, the time is ripe for additional research on the topic. The potential for “cross-pollination” of ideas from charters to traditional schools may hold its greatest potential in districts that authorize the charters in their school district.

Some questions for researchers to consider:

  • What are the ingredients that contribute to charter school success? Do smaller class size, longer days, parent involvement, or freedom from collective bargaining and other regulations play a part? What variables count most?
  • What effects do different governance models have on positive charter school outcomes?
  • What interaction exists between traditional and charter public schools? Is there any evidence of shared ideas and information? Innovation? Does the charter’s authorizer affect the results?
  • How do charter schools affect traditional public school funding?
  • What are charter schools’ effects on local school districts in terms of funding, governance, logistics and accountability, as well as performance?

Questions for school boards

  • Which agencies does our state empower to authorize charter schools? How does the local school board fit into the authorizing process?
  • What is our opinion of, and relationship with, EMOs?
  • What is the state process for evaluating whether local charter schools are in fact improving achievement? What is the local role?
  • Is there a process for closing underperforming charter schools prior to their renewal date? How long is the time span before renewing a school’s charter? What is the local school district role?
  • Does our state have caps or an appeals process for the creation or removal of charter schools?
  • What is the interaction between charter and traditional public schools? Does it matter if the local school board was the authorizer, or if there was another authorizer?
  • What lessons could we apply from local or national charter schools about school size, instruction, etc. to our traditional public schools?

Conclusions and next steps

It is clear that charters are poised for another growth spurt due to actions taking place at the federal level. Through its Race to the Top competition, the U.S. Education Department is providing a powerful incentive for states to boost their support for charters. In addition, the Obama administration, in its public pronouncements, has advocated the benefits of these schools. These factors are likely to generate greater interest in the issue not only in urban areas but also in suburban and rural districts.

What do we know, then, about charter schools as a reform strategy? As noted earlier, the research base is thin. However, data from major studies seem to indicate that students attending charters exhibit stronger gains in math at the elementary level and in reading at the middle school level than those at traditional public schools, but on the other hand few gains for those at charter high schools and multi-level charter schools. In addition, at least one major study (CREDO 2009) has found that, looking beyond individual student achievement to school-wide performance, only 17 percent of charters fared significantly better than typical public schools while 37 percent performed significantly worse.

Given the research base, any explanation of why some charters succeed and others don’t is speculative. A possible answer is that successful charter schools use strategies that research has proven are often effective—smaller class size, more school time, and greater parent involvement. Whether hallmarks of charter schools such as a lack of collective bargaining or greater autonomy affect achievement is not known, and should be researched.

As noted earlier in this study, many different agencies may authorize charter schools depending on the state law governing their creation and operation. Given this trend, local school board involvement in the issue varies greatly. A growing number of charters also are run by educational management organizations, which may include for-profit or non-profit agencies that run multiple schools across one or more states. Through this arrangement, many EMOs capitalize on economies of scale to deal with administrative and operational challenges that can frustrate new schools.

Recognizing all of these factors, state school board associations and individual board members face significant challenges in assessing the issue of charter schools. Of paramount importance for board members is whether, and if so, how, they have a strong voice in the decision-making process in their geographic areas. Among many needs in the next phase of charter school research, it is imperative to examine the performance of charters authorized by local school boards and whether this factor contributes to positive outcomes. Such research would provide a timely addition to inform state and local policy on this high-priority issue.

This report was prepared for the Center for Public Education by Eileen M. O’Brien and Chuck Dervarics. O’Brien is an independent education researcher and consultant in Alexandria, Virginia. Much of her work has focused on access to quality education for disadvantaged and minority populations. O’Brien has a Master of Public Administration from George Washington University and a Bachelor of Science degree in psychology from Loyola University, Chicago. Chuck Dervarics is an education writer and former editor of Report on Preschool Programs, a national independent newsletter on pre-k, Head Start, and child care policy. As a writer and researcher, he has contributed to case studies and research projects of the Southern Education Foundation, the American Council on Education, and the Massachusetts Board of Higher Education, often focusing on issues facing disadvantaged populations. Dervarics has a Bachelors degree from George Washington University.

Posted: March 24, 2010

©2010 Center for Public Education