Systematic Review of Enrollment of Students With Disabilities in Charters Compared to Traditional Public Schools

Abstract

There is a perception that charter schools in the United States enroll students with disabilities at a lower rate than traditional public schools despite federal laws that require charter schools to provide the same services as traditional public schools. This systematic review answers the question: What research exists that explores the representation of students with disabilities in charter schools and the proportionality of that representation in comparison to traditional public schools? The methodology for this review was based on the PRISMA (Preferred Reporting Items for Systematic review and Meta-Analyses) statement for reporting systematic reviews. Conclusions from this review include the limited amount of research on the topic, the difficulty of comparing enrollment percentages between state systems, and the difficulty in determining factors affecting the enrollment of students with disabilities in charter schools.

Keywords

civil rights law/legal issues policy

The Individuals with Disabilities Education Act (IDEA) provides for the free and appropriate public education of students with disabilities in all public schools in the least restrictive environment. Federal case law (Brown v. Board of Education) has also decreed that educating minority populations, such as students with disabilities, in separate settings does not provide an equal education. Currently, the legal premise for equitable education for students with disabilities is being debated regarding public charter schools.

The charter school movement has been gaining momentum in the United States over the past 30 years and has recently become politicized, with various political parties holding different positions regarding use of charter schools (Lancet et al., 2020). Charter schools are autonomous schools that began operation under the belief that parental choice in schools would drive market-based accountability, leading to “more innovative and effective learning environments” (Rhim & McLaughlin, 2007). Since the first charter school law was passed in Minnesota in 1991, 44 states, Washington D.C., and three territories have enacted charter school laws, which govern approximately 7,500 charter schools, educating 3.3 million total students—approximately 6.5% of the total student population during the 2020 to 2021 school year (National Alliance for Public Charter Schools, 2020 Annual Report, 2020). Each state and territory where charter school laws exist has its own legal system for authorizing and monitoring public education in charter schools, which can make comparing charter schools on a national scale difficult. For example, states can choose whether or not to classify charter schools as local education agencies (LEAs). This classification gives them full autonomy over special education assessments, placements, and funding decisions. Some states elect to classify charter schools as LEAs; others pair charter schools with an existing LEA, removing much of their special education decision-making; and other states offer both options. Charter schools’ LEA status is determined at the time of authorization. As may be guessed, this difference between states on charter school classification can lead to differences for special education enrollment and services in charter schools, making direct comparisons of representation between states difficult.

However, as noted, special education services for students with disabilities are governed by federal legislation and legal precedence, which means services should be equitable across state and school settings. Federal laws that apply to students with disabilities include the IDEA 2004, Section 504 of the Rehabilitation Act (Section 504), and the Americans with Disabilities Act. Because of this, charter schools, as public education entities that receive federal funding, have the same legal obligations to enroll students with disabilities as traditional public schools regardless of differing state laws.

There is a perception that charter schools enroll a disproportionately lower number of students with disabilities than traditional public schools and may actively discourage students with disabilities from applying to charter schools (National Center for Special Education in Charter Schools [NCSECS], 2016). This perception is concerning enough that several states have set up programs to monitor and educate charter school enrollment staff on their responses to parents of potential charter school students with disabilities (NCSECS, 2016). If charter schools are enrolling students with disabilities at a lower rate than traditional public schools, charter schools could be seen as exclusionary settings that do not provide equal educational opportunities for students with disabilities despite federal legislation and case law that guarantees equal opportunities for students with disabilities across preK–12 education settings.

A separate issue is the increasing number of specialized charter schools that have been tailored to meet the needs of students with specific disabilities. These specialized charter schools add additional questions around the equitable education of students with disabilities as they can be viewed as exclusionary settings where students with disabilities are not educated in the least restrictive environment with their non-disabled peers as required by IDEA. These charter schools also tend to skew comparisons of representation between charter schools and traditional public schools by increasing the average rate of representation of students with disabilities in charter schools. As Rhim et al. (2019) stated,

The challenge before both the traditional public and charter school sectors is to ensure that the programmatic innovation and excellence provided by the best specialized schools exist without having specialized schools become the default or only option for students with disabilities (p. 27).

According to the National Alliance for Public Charter Schools’ 2020 Annual Report, 3.3 million students are currently educated in charter schools and the number of charter schools has increased by three times since the 2005 to 2006 school year (National Alliance for Public Charter Schools 2020 Annual Report, 2020). The National Center for Education Statistics estimated 50.7 million students attended public schools in the United States during the 2020 to 2021 school year (The NCES Fast Facts Tool Provides Quick Answers to Many Education Questions, 2020). Based on these numbers, approximately 6.5% of students in the United States attended a charter school during the 2020 to 2021 school year. Although the percentage of students enrolled in charter schools in the United States is far from a majority, the expansion of charter schools and charter school legislation point to the need to ensure that charter schools are not evolving into separate education settings that exclude minority populations.

Because of the continued expansion of charter schools, their role in public education, and the perception that students with disabilities are enrolled in charter schools at a lower rate than their able-bodied peers, well-designed studies are needed to inform our understanding of the representation of students with disabilities in charter schools. Currently, there are no systematic reviews of literature that describe what research has been completed on this topic and the quality of those studies. The purpose of this article is to document a systematic review of literature to answer these questions: What published research exists that explores the representation of students with disabilities in charter schools and the proportionality of that representation in comparison to traditional public schools and what quality is that published research based on threats to study validity?

This study is a systematic literature review and, as such, relies on published sources. The focus on published research allowed the authors to determine the quality and validity of the study results produced by primary research. The systematic literature review was expanded to cautiously include some non-academic research conducted as self/third-party studies that were of sufficient quality and provided useful information on the topic of charter school enrollment of students with disabilities. This systematic review was completed in preparation for a state-level primary research effort to review enrollment comparisons of students with disabilities and implementation of IDEA between charter schools and traditional public schools directly.

Method

The foundation of the methodology for this systematic review was based on the PRISMA statement for reporting systematic reviews and utilized the population, interventions, comparator group, objective, and study design criteria (Liberati et al., 2009). For this study, the criteria included: population, students with disabilities enrolled in preK–12 education in the United States; intervention, enrollment of students with disabilities in public charter schools; comparator group, enrollment of students with disabilities in traditional public schools; outcomes, determination of the representation of students with disabilities between charter schools and traditional public schools; and study design, quantitative and mixed methods studies comparing enrollment of students with disabilities between charter schools and traditional public schools.

Literature Search, Screening, and Coding Procedures

For this study, students with disabilities were defined as students having an Individualized Education Program (IEP) under IDEA. Students receiving services for a disability under Section 504 were not included as most published studies do not include data on these students when determining enrollment rates of students with disabilities. IDEA was last reauthorized by Congress in 2004, and at that time, many reporting additions for states were added and revisions were made to the 13 categorizations of disabilities students can receive services for. These revisions changed how states and territories tracked and reported data on how well IDEA is being implemented in all schools in their state or territory. Because of this, no literature published before 2004 was considered in this systematic review as it would have been framed under a different legal equity standard than what charter schools are held accountable for today.

Database searches were conducted using Education Source, ERIC, and PsycINFO. Education Source and ERIC were included as they focus on education research. Many assessments to determine if a student has a disability are conducted by school psychologists and this professional is instrumental in providing many services to students with disabilities. Because of this, PsycINFO was also selected as it is a top database resource for psychology research, which includes research on behavioral sciences that touch on many disability topics.

Search terms used with each database included “students with disabilit*” AND “charter school*” AND “enrollment” OR “identif*” OR “represent*.” Abbreviated terms with asterisk were used to capture all configurations of terms such as: disability* (disability or disabilities), school* (school or schools), identif* (identify or identification), and represent* (represent, representative, and representation). The search terms were further refined by the study’s inclusion criteria, selecting options to only show results published between 2004 and 2021, articles published in English (the researcher’s primary language, and most likely given the U.S. context of charter school research), and results with the full text available to review. For the search in PsycINFO, the search was also further refined to exclude dissertations. PsycINFO was the only database that allowed for this refinement selection. Dissertations were excluded as they did not fit into the categories of peer-reviewed or self/third-party reports outlined in the following paragraph.

Because of the variety of literature on the topic, peer-reviewed, self-reports, and third-party reports were all included as options in the inclusion criteria. It was decided that as part of the study, separate analyses would be conducted for the peer-reviewed articles and the combined self/third-party reports. This allowed for the discussion to include a comparison of the reviews of peer-reviewed and non-peer-reviewed sources. Barnard-Brak et al. (2018) noted that while self/third-party reports provide useful information on the topic of charter school enrollment of students with disabilities, the scholars writing the reports can be affiliated with organizations that promote and support charter schools and potentially their reports may be influenced by confirmation bias. In short, their “potential conflicts of interest can create a situation where scholars are seeking evidence (e.g. variables and samples) that confirm the agenda of these organizations” (p.18).

In summary, the eligibility requirements for inclusion in this review included:

Studies that are peer-reviewed, self-study, and third-party reports.

Studies published since 2004 when IDEA was reauthorized and indicators were established to evaluate state efforts to implement the requirements of IDEA.

Studies published in English (the researcher’s primary language and the primary language of research published in the United States).

Studies based on representation of students with disabilities in charter schools in the United States because the study is premised on case law and legal requirements in the United States where charter schools have the same legal responsibilities to enroll students with disabilities as traditional public schools.

Studies employing quantitative or mixed methods analysis to determine representation of students with disabilities in charter schools.

The literature search process returned 364,839 journal articles. Because of a large number of articles returned, the researcher downloaded the first 1,000 articles returned for each database (3,000 total downloaded). The articles were screened using Zotero software for duplicates (162 removed), leaving 2,838 to be screened. The researcher screened the articles’ titles and abstracts for inclusion based on the eligibility requirements for inclusion. After the titles and abstracts were screened for the study’s inclusion criteria, 19 studies remained. The excluded studies included phrasing from the search terms in their titles and abstracts but did indicate in their titles and abstracts that they related to representation of students with disabilities in charter schools.

During full-text coding, five of these articles were excluded because two were duplications of other identified articles and the other three did not meet the systematic review’s inclusion criteria. Two of the three articles that were rejected for not meeting the inclusion criteria addressed alternative, but related topics, including how charter schools greet parents of students with disabilities (NCSECS, 2016) and how special education funding affects traditional public schools and charter schools (Marchitello et al., 2019). The third article that was rejected during full-text coding was a short news article (Hehir, 2010). Following the full-text review of the remaining 14 studies, an ancestral search was performed on the citations in those studies. A further six articles were identified for full-text coding based on their titles and abstracts. Subsequently, four of those articles were included in the final synthesis with one excluded because it was a duplicate of a study in another article, and one was excluded for not meeting the review’s inclusion criteria. Following the full-text review of the six articles identified in the ancestral search, an ancestral search was performed on the references in those studies and no further articles were found that met the inclusion criteria. In total after exclusions during the full-text review, 18 studies (10 peer-reviewed and eight self/third-party reports) were included in the final synthesis.

During the full-text review of the identified articles, the articles were coded to ensure they met the study’s inclusion criteria. The coding form was created in Microsoft Excel with 17 data items collected for each article. Excel was the chosen software because it was familiar to the researcher and would increase efficiency in coding. The coding categories included: author’s last name/year of publication, article title, research question(s), sample size, grade levels included in the study, location of the study, research design, sampling technique, independent variable, dependent variable, data collection technique, threats to validity, data analysis methods, author’s conclusions, methodological quality, and coder’s notes.

Quality Assessment

The researcher used a threats-to-validity approach to evaluate the quality of the coded studies (Cooper, 2017). This quality assessment was selected because the descriptive research designs employed in most of the identified studies did not allow for a meta-analysis or deep comparison of statistical methods employed by the studies. The threats-to-validity approach allowed “less-than-optimal designs” to be “triangulated so that strong inferences could result from multiple studies when the single ‘perfect’ study could not be performed” (Cooper, 2017, p. 164). Following this method, each article was reviewed for threats to internal, external, construct, and statistical validity. Based upon the threats to validity that were identified for each study, the researcher reviewed whether each article’s conclusions could accurately be based upon their analysis or if there was an alternative explanation for explaining the results. Following this, the researcher was able to rank articles from lower to higher quality and compare if lower quality studies had similar outcomes to higher quality studies. The researcher was also able to compare study quality between the peer-reviewed articles and the self/third-party articles. These comparisons allowed the researcher to triangulate results and conclusions from the various studies to see if conclusions from peer-reviewed articles and the self/third-party studies corroborated. Also, as part of the quality assessment, the articles were reviewed for any possible researcher biases that may have been present.

Data Analysis

Due to the diversity of research meeting the inclusion criteria, a meta-analysis was not possible. Therefore, the researchers conducted a systematic literature review of the quality of the articles with inferences outlined from the synthesis of information. The synthesis of information included comparing and contrasting the articles’ methods and results, critically evaluating the findings through the quality assessment, interpreting the study, and drawing conclusions.

Results

A total of 18 studies were selected for the review after the full-text review. These included 10 peer-reviewed studies and eight self-third-party reports.

Results From the Peer-Reviewed Studies

Of the 10 peer-reviewed articles selected for the study, seven employed a quantitative research design and three employed a mixed methods research design. Excluding the interview data and document analysis employed in the mixed methods studies, all of the articles utilized secondary data gleaned from national school data reports or state/city/district education agencies. All of the studies stated a research purpose(s) or question(s) that related to representation of students with disabilities in charter schools. It should be noted that one of the studies (Wilkens, 2011), addressed the placement of students with disabilities in the regular classroom (or least restrictive environment) by charter schools compared with traditional public schools, which the researcher felt was pertinent to the question of representation of students with disabilities in charter schools as several of the other articles reported the ability of charter schools to accommodate students with disabilities in the regular classroom without a disability classification. Also, Zimmer and Guarino (2013) addressed “low-achieving students” instead of students with disabilities. The researcher decided to include this article in the review, as the authors discussed the inclusion of students with disabilities in the label of “low-achieving students” and they determined whether or not charter schools were pushing these students out of their schools. Although it was decided that studies published before the reauthorization of IDEA in 2004 would not be included in the study, it should be noted that Estes (2004), Wilkens (2011), Zimmer and Guarino (2013), and Setren (2020), all used student enrollment data gathered before 2004. Although the reauthorization would not have affected the how enrollment data were obtained by education agencies, it would have affected the determination of disability type and it is important to note this for these studies. All but one of the peer-reviewed studies were also completed on a limited geographic scale, either for a certain school district, city, or state.

To assess the quality of the articles, a threats-to-validity approach was used to assess the construct, statistical, internal, and external threats to research validity for each article. Articles were also reviewed to note any researcher bias that may have been apparent. As previously noted, all of the peer-reviewed studies relied on secondary data, and in doing so, are open to any errors the primary data may have contained. For the purposes of this study, it was impossible to determine if any of the data was flawed and so no analysis was completed on the validity of study data. However, it should be noted that any study analyzing enrollment data that was not conducted by the school gathering the data will be forced to utilize secondary data. Although this is a note of concern for the studies, it is not something that can not be helped when considering this topic.

When reviewing for threats-to-validity, one article, Wolf (2011), did not provide enough information to determine if there was construct validity, and three articles, Wolf (2011), Winters (2015), and Setren (2020), did not provide enough information to determine if there was statistical conclusion validity. Three articles, Estes, (2004), Arcia (2006), and Estes (2009), contained threats to statistical validity as they only used enrollment data from one school year. Since charter schools can have low total enrollment numbers, using multiple years of enrollment data would strengthen statistical validity by providing a more accurate picture of charter school enrollment. Nine of the 10 peer-reviewed articles contained external validity threats regarding population generalization, as they reviewed data limited to a single state, city, or school district. The differing laws between states regarding charter schools also make it difficult to generalize study data between education systems. Only one article, Barnard-Brak et al. (2018), utilized national data and was not deemed to have a population generalization validity threat. One article, Wolf (2011), was noted as containing researcher bias as the author explained they had worked as a reform consultant in the study location and could not keep their experiences completely separate from their research. No threats to internal validity were identified.

Overall, the results of the peer-reviewed articles were mixed. Five of the articles indicated that students with disabilities were enrolled in charter schools at a lower rate than the traditional public schools in their data sets and two articles indicated that charter schools enrolled a higher percentage of students with disabilities compared with the traditional public schools in their data set.

Conclusions that stood out from the studies were:

District averages for students with disabilities are not an appropriate measure to gauge individual school enrollment of students with disabilities (Arcia, 2006).

Charter schools place students with disabilities in the regular classroom at a higher rate than traditional public schools, but they enroll fewer disability types that have low regular classroom inclusion rates (Wilkens, 2011).

In one study location, students with disabilities were being denied admission to charter schools (Wolf, 2011).

Low-achieving students were more likely to transfer out of traditional public schools than charter schools, with no evidence that charter schools were pushing low-achieving students out of their schools (Zimmer & Guarino, 2013).

The gap in enrollment rates between charter schools and traditional public schools was due to identification rates and the types of disabilities at charter schools (Winters, 2015 and Winters et al., 2017).

The number of students with disabilities applying to charter schools was similar to the rate of students with disabilities enrolling in traditional public schools (Setren, 2020).

Results from the Self/Third-Party Reports

Seven of the self/third-party reports employed a quantitative research design and one report employed a mixed methods analysis by including site visits and interviews. Similar to the peer-reviewed articles, all of the reports utilized secondary data gleaned from national school data reports or state/city/district education agencies. All of the studies stated a research purpose(s) or question(s) that related to representation of students with disabilities in charter schools. It should be noted that many of the self/third-party reports not only proposed a research purpose(s) or question(s) that probed representation of students with disabilities in charter schools but also included purposes or questions posed to explain why there was a difference in enrollment rates.

To assess the quality of the self/third-party reports, a threats-to-validity approach was used to assess the construct, statistical, internal, and external threats to research validity for each study. Reports were also reviewed to note any author bias that may have been apparent. As previously noted, all of the self/third-party reports relied on secondary data, and in doing so, are open to any errors the primary data may have contained. For the purposes of this study, it was impossible to determine if any of the data was flawed and so no analysis was completed on the validity of study data. However, it should be noted that any report analyzing enrollment data that is not conducted by the school gathering the data will be forced to utilize secondary data. As previously noted, this is a point of concern for the reports, but it is not something that can be helped when considering this topic.

When reviewing for threats-to-validity, two reports, Scott and Government Accountability Office (2012) and Winters et al. (2013), did not provide enough information to determine if there was statistical conclusion validity. Three reports, Lake et al. (2012), Winters et al. (2013, 2014), of the eight self/third-party reports contained external validity threats regarding population generalization, as they reviewed data limited to a single state, city, or school district. Five of the reports utilized national data and were not deemed to have a population generalization validity threat. Seven reports were noted as containing possible researcher bias as they were produced or funded by organizations promoting or supporting charter schools. The other report, Scott and Government Accountability Office (2012), was a federal report completed by the U.S. Government Accountability Office and was the only report not published or funded by an organization promoting or supporting charter schools. No threats to internal validity were identified.

Overall, the results of the self/third-party reports were more decisive regarding the representation of students with disabilities in charter schools. Five of the reports indicated that students with disabilities were enrolled in charter schools at a lower rate than the traditional public schools in their study location. One report noted that enrollment of students with disabilities at middle and high school charters were indistinguishable from traditional public schools in their study location and that only charter elementary schools showed under enrollment of students with disabilities (Lake et al., 2012). Instead of spending time illustrating the data for the enrollment rates, many of the reports devoted significant time further disaggregating enrollment data to determine why there was a gap in enrollment of students with disabilities between charter schools and traditional public schools.

The following conclusions stood out from the reports:

Statewide differences in enrollment rates of students with disabilities at charter schools and traditional public schools are too simplistic of a comparison. Variation among charter school authorizers may contribute to differences in enrollment rates (Lake et al., 2012).

The proportion of charter schools that enroll high percentages (8–12%) of students with disabilities was lower than traditional public schools overall. However, a higher percentage of charter schools had a 20% or higher enrollment percentage of students with disabilities (Scott & Government Accountability Office, 2012).

Students with autism and speech disabilities are less likely to apply to charter schools. The enrollment gap between charter schools and traditional public schools is due to lower identification of students with disabilities in charter schools. Students with disabilities are less likely to transfer out of charter schools than traditional public schools (Winters et al., 2013).

Efforts to address disproportionate representation of students with disabilities in charter schools that focus on charter schools counseling out students with disabilities are unlikely to be productive (Winters et al., 2014).

Charter schools that operate as their own LEA enrolled more students with disabilities than non-LEA charter schools (Rhim et al., 2018 and Lancet et al., 2020).

Charter schools enrolled a higher percentage of students with SLD and emotional disturbance than traditional public schools and a lower percentage of students with development delays and intellectual impairments. Charter schools enrolled students with disabilities in more inclusive settings (Rhim et al., 2015 and Rhim et al., 2018).

The popularity of specialized charter schools for students with disabilities continues to grow (Rhim et al., 2019).

National enrollment averages mask significant variances between states. Enrollment rates of students with disabilities in charter schools depend on the evaluation/identification process, LEA status/relationship, and oversight/accountability of special education services (Lancet et al., 2020).

Comparison of Studies Based on the Quality Assessment

Another purpose of this systematic review was to compare if low quality studies had the same results as high-quality studies. Due to the nature of the topic and the usage of secondary data to provide descriptive statistics in most of the studies, there were few factors to review in the threats-to-validity quality assessment. Studies that were deemed low quality, either lacked enough information to make a validity determination, had a population generalization threat to external validity, or only used one year of data. The three studies that only used one year of data were deemed to be the lowest quality. These studies reported results that included 70% of the charter schools in the study location enrolling fewer students with disabilities than the state average (Estes, 2004), traditional public schools were significantly more likely to compare to the district average of students with disabilities than charter schools (Arcia, 2006), and students with disabilities were represented in charter schools at a higher rate than the state average (Estes, 2009). All three of these articles were peer reviewed and add to the mix of results for different study locations that speaks to how differing charter school laws affect enrollment of students with disabilities in charter schools.

Comparison of Peer-Reviewed and Self/Third-Party Reports

While reporting on representation of students with disabilities in charter schools there were several differences between the two groups of literature. As noted earlier, many of the self/third-party reports not only proposed a research purpose(s) or question(s) that probed representation of students with disabilities in charter schools but also included purposes or questions that attempted to explain why there was a difference in enrollment rates. For example, the peer-reviewed articles stated questions around whether segregation was occurring in charter schools, if charter schools were meeting special education legal enrollment requirements, or if charter schools were pushing out students with disabilities. In contrast to this, the self/third-party reports stated questions around the disability classification distribution between charter schools and traditional public schools and what factors contribute to differences in enrollment. Because of this, many of the self/third-party reports reported outcomes related to factors that contributed to the enrollment discrepancy between charter schools and traditional public schools, such as the higher rate of inclusion of students with disabilities in the regular classroom in charter schools, the difference in disability types attending charter schools, and the lower classification rates of students with disabilities in charter schools.

Another difference between the peer-reviewed and self/third-party reports was the usage of national data. Only one of the peer-reviewed studies used a national data set while five of the eight self/third-party reports used national data. Many of the studies noted that national data could mask variances in the data and could not provide a direct comparison between charter schools and traditional public schools because of the differences in state charter laws (Lancet et al., 2020). Because of this, many of the peer-reviewed studies focused on one education system (state, city, or district-level). However, the self/third-party reports that utilized national data focused on showing the complexity of the issue and the factors that affected the data. One explanation for this may be the easy availability of national data to the organizations that published the self/third-party reports.

Another variance between the peer-reviewed studies and self/third-party reports was the number of articles that stated that students with disabilities were under represented in charter schools. All of the self/third-party reports stated that students with disabilities were under represented in charter schools while two of the peer-reviewed articles found that students with disabilities were more highly represented in charter schools. This difference may be attributed to the difference in data sets. The factors identified by several of the articles as affecting enrollment of students with disabilities in charter schools (LEA status, authorization process, disability classification rates, and monitoring of services) would be more apparent in localized studies than in aggregate national data.

Also as noted previously, the results of the self/third-party reports were more decisive regarding representation of students with disabilities in charter schools. Five of the reports indicated that students with disabilities were enrolled in charter schools at a lower rate than the traditional public schools in their study location. This decisiveness may be due to the usage of national data in three of those studies. With the large sample prepared by the Office of Civil Rights, those studies could easily determine a total enrollment comparison and then delve into exploring reasons for the disproportionate representation. The other two studies also looked at larger educational systems (New York City and Denver, CO). With larger data compilations, the reports could more easily review the total enrollment comparison and then delve into further analysis by disability type or other factors. The peer-reviewed studies that looked at smaller, district-level systems had smaller samples of data to disaggregate and make determinations from.

The major similarity between the peer-reviewed articles and the self/third-party reports was the emphasis on ensuring that students with disabilities were provided equal access to charter schools and that IDEA requirements be adhered to in all school settings. Although the articles and reports differed on if there was disproportionate representation of students with disabilities and what factors contributed to it, all of the articles included discussion that explained the need to educate students with disabilities in both charter schools and traditional public schools and promote increased educational outcomes for those students.

Discussion

The majority of the studies reviewed in this systematic review indicated students with disabilities were under-represented in charter schools or started with a statement that students with disabilities were under-represented in charter schools and further disaggregated the data to determine why the representation variance existed. Despite this fairly consistent result of lower enrollment rates of students with disabilities in charter schools, the existing research also suggests that it is difficult to holistically determine if students with disabilities are enrolled in charter schools more or less than traditional public schools. The studies were also very careful in how they reported the representation of students with disabilities in charter schools. In most cases, the articles would report or state that students with disabilities were under-represented in charter schools in a certain geographic area, but then provided reasons for the gap in enrollment.

From what the research reports, enrollment of students with disabilities in charter school is based on how charter schools evaluate for and identify disabilities, the LEA classification of the charter school, and how the oversight and monitoring of special education programs is conducted at the school. Another issue when reviewing data on the enrollment of students with disabilities in charter schools is whether or not specialized charter schools that operate under missions focused on serving students with disabilities are included or excluded from the data analysis. Nearly all of the studies reviewed in this paper did not indicate whether or not specialized charter schools were included in their data analysis. The inclusion of a specialized charter school with a student body consisting only of students with IEPs in a data set can skew the data analysis. Because of these factors, the literature on enrollment of students with disabilities in charter schools clearly shows this is a nuanced issue that is as complex as the U.S. education system. There is no definitive answer as to whether or not students with disabilities are under or overrepresented in charter schools because of these confounding factors.

It is also interesting to note, how study quality related to the results of each study. Studies that determined that charter schools had lower enrollment rates for students with disabilities than traditional public schools ranged between having zero and four validity concerns. All of the studies that determined that charter schools had higher or similar enrollment rates of students with disabilities compared with traditional public schools had two validity concerns. Although it is difficult to make a solid determination regarding enrollment rates from this comparison because of the low number of studies available for comparison, study quality does not appear to affect the reported enrollment results for the studies.

One hypothesis that could be hazarded based upon the existing research, is that while students with disabilities are present in charter schools (and sometimes at comparable rates to traditional public school in the same geographic area), that the demographics of those students may not mirror the demographics of the students with disabilities in traditional public schools. Charter schools may be predisposed to attract and retain students with certain disability classifications and age groups as charter schools are more prolific for secondary grades (6–12) than elementary grades (preK–5). For example, fewer students with speech disabilities may be enrolled in charter schools as the students are more likely to utilize speech services in elementary grades. Even charter schools that offer elementary grades may enroll fewer students with speech disabilities if they don’t offer preschool services when many students begin speech services and may be less likely to transfer from the traditional public school where they began preschool to a charter school for kindergarten (Winters, 2015).

One item that was clear across both the peer-reviewed studies and the self/third-party reports is that national data cannot provide direct comparisons between enrollment rates of students with disabilities in charter schools and traditional public schools. The variance in state and territory charter laws greatly effects how charter schools enroll and provide services for students with disabilities. So, while services for students with disabilities are mandated and monitored for compliance under federal legislation, the education systems set up and operated in each state and territory are diverse enough that any review of enrollment of students with disabilities in charter schools needs to be completed for specific state education systems. The variance between charter school laws between states and territories and its effects on special education is not a new idea in charter school research. However, it is clear from the results of this study that there is no published peer-reviewed or self/third-party reports that review representation of students with disabilities between charter schools and traditional public schools at a state or territorial system level and this points to the need for such analyses.

Taking this further, monitoring of enrollment rates and disability classifications should also be completed at the local level (school district and individual charter schools) to ensure that charter schools are providing enrollment and special education services for students with disabilities that are equitable to those in the statewide education system they are located in. This would provide a more accurate analysis of charter school enrollment than simply reviewing national data and would allow states and school districts to ensure that special education services are equitable and provide optimal outcomes for students with disabilities.

This monitoring and analysis could also include a review of outcomes of students with disabilities in charter schools and traditional public schools. Because the foundational purpose of charter schools is to provide settings where parental choice drives accountability for student outcomes, leading to innovation and effective learning, if monitoring found that students with disabilities were achieving better outcomes in charter schools, those innovative and effective learning strategies could be promoted as teaching strategies for traditional public schools as well. The reverse could also be done for traditional public schools that have high outcomes for students with disabilities and the promotion of those methods in charter schools.

A final discussion item is the sources sponsoring the self/third-party reports. It was noted earlier that self/third-party reports may have the potential for confirmation bias. However, the organizations publishing the self/third-party reports were reviewed and while there may be potential for some confirmation bias, the mission and vision statements of the organizations sponsoring the third-party reports address the support and equitable access of students with disabilities in charter schools. Three of the third-party reports were published by the Center on Reinventing Public Education (CRPR), an externally funded organization affiliated with the University of Washington. CRPR focuses on making public education more effective and has no stated preference for charter schools compared with traditional public schools. Four of the third-party reports were published by the National Center for Special Education in Charter Schools (NCSECS). NCSECS has vision and mission statements that promote equitable access for students with disabilities in charter schools. Although there is potential for NCSECS to publish materials that bolster their vision and mission statements, all four studies published by them utilized national data from the Office of Civil Rights and provided a disaggregation of enrollment data that can be easily verified and provided a current picture report of enrollment of students with disabilities in charter schools. The one self-report used in this review was published by the U.S. Government Accountability Office (GOA). As the GOA is charged with providing fact-based, non-partisan information to Congress, its report was ruled out as containing confirmation bias.

Limitations

Limitations to this systematic review include the inability to provide a meta-analysis or full review of the data used in the articles. This was due to the usage of secondary data to produce descriptive statistics by all of the studies. This was because of the nature of reviewing school enrollment data and the fact that any study would be forced to utilize secondary data.

Implications for Research

The opportunity for future research around the representation of students with disabilities in charter schools is wide. As it enters its fourth decade, the charter school movement is still young, and research on its effects on U.S. educational systems and outcomes for students with disabilities is in its infancy. This systematic review found only 18 peer-reviewed articles and self/third-party reports that reviewed the representation of students with disabilities in charter schools, making it clear that more well-designed studies are needed to understand the topic. The discussion around equitable access for students with disabilities will not abate and will continue to grow as charter schools continue to expand.

As noted, there is a need for research on enrollment of students with disabilities in charter schools in all state and territorial education systems that have charter school laws. This research will help each state or territory identify if there is a significant difference in enrollment rates between charter schools and traditional public schools in their system, what factors may be influencing charter school enrollment of students with disabilities, and what policy or monitoring changes may need to be made to promote equitable learning environments between charter schools and traditional public schools.

Another future research need is an analysis of how well charter schools are implementing IDEA. Each state and territory is required to submit an Annual Performance Report (APR) that reports on how well they are implementing the requirements of IDEA. To prepare the report, each state and territory collects data from LEAs on how well they are implementing IDEA. Research could be conducted to see how charter schools that operate as an LEA perform on the APR data they submit to the state. This comparison could include comparisons between charter schools and traditional public schools with high enrollment rates of students with disabilities and low enrollment rates of students with disabilities to see where students with disabilities are receiving special education services and how well they are being served.

Conclusion

The current political climate has seemingly degraded the discussion around charter schools to a simple matter of favoring them and disfavoring them. However, it is very clear from the research reviewed in this systematic review that charter schools are here to stay and the matter is much more complicated than the perception that charter schools may be enrolling students with disabilities at a lower rate than traditional public schools. With the differing charter school laws across the United States, each state or territory that allows charter schools needs to examine their own system and review the factors that are affecting enrollment of students with disabilities in charter schools and ensure that their education system is providing equitable education opportunities for all students. It is also clear that much more research is needed on the topic to not only gauge representation of students with disabilities in charter schools but also review how charter schools are implementing IDEA compared with traditional public schools.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

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