Last November, the Mattone Center co-hosted a regional conference of the International Consortium for Law and Religion Studies. The conference, “Education, Religious Freedom, and State Neutrality,” brought together scholars and jurists from the United States and Europe to compare approaches to these subjects in their respective countries. Participants were invited to submit short reflections. Víctor Moreno Soler (University of Valencia) submitted the following reflection, which we are delighted to publish here.
I. Introductory remarks
The debate surrounding single-sex education (SSE) raises a fundamental question: Does SSE deliver developmental benefits and encourage women to enter nontraditional fields, or does it allow gender stereotypes to go unchallenged?[i] This issue reflects a complex negotiation between three core principles: parental rights, understood as the freedom to choose the educational model that best aligns with family values; institutional freedom, referring to the autonomy of the center to define their pedagogical identity; and the public interest, which upholds the principles of equality and non-discrimination, as well as the best interests of the child.
It is important to emphasize that single-sex schools are not necessarily religious, and religious schools are not necessarily single-sex. A wide variety of institutional models and rationales exist behind the provision of SSE, ranging from pedagogical theories to cultural or religious convictions.
Some scholars argue that SSE is based on the premise that men and women differ biologically, psychologically, and developmentally. From this perspective, SSE is not merely a pedagogical model, but a response to those differences aimed at improving educational outcomes. Others, however, contend that such schools may not provide the most conducive environments for girls’ social and academic development and might risk reinforcing gender stereotypes or traditional gender roles.
The purpose of this analysis is not to determine whether single-sex education is pedagogically desirable. Instead, it is to consider the extent to which schools adopting this model may claim access to public funding.
II. International Regulatory Framework
At the international level, there are key instruments that address single-sex education, establishing its legality provided that equivalence criteria are met.
1. The 1960 UNESCO Convention against Discrimination in Education.
This Convention is the first binding international legal instrument dedicated entirely to the right to education. It plays a pivotal role in legitimizing single-sex education, provided certain conditions are met.
First, it explicitly states that the establishment or maintenance of separate educational systems or institutions for male and female students shall not be considered discriminatory.
It then sets out the criteria for compliance: institutions must offer equivalent access to education, employ teaching staff with qualifications of the same standard, ensure school premises and equipment of comparable quality, and provide students with the opportunity to pursue the same or equivalent courses of study (Article 2.a of the 1960 UNESCO Convention).
Another distinct issue — the one directly at stake here — is the question of whether this SSE may claim a right to state funding. This Convention does not provide any guidance on this matter, as none of its provisions addresses the public funding of single-sex education.
2. The 1979 Convention on the Elimination of All Forms of Discrimination against Women (CEDAW).
This Convention does not prohibit single-sex education, even though it appears to promote coeducation. In fact, it encourages “coeducation and other types of education which will help to achieve this aim (the elimination of any stereotyped concept of the roles of men and women).” (Article 10.c).
We must ask whether single-sex education inherently reflects or reinforces stereotyped conceptions of the roles of men and women. Regardless of the model, CEDAW establishes that States Parties are obligated to take all appropriate measures to ensure equal conditions for access to education—including access to curricula, examinations, teaching staff, equipment, and scholarship opportunities.
These requirements apply to all educational settings, including single-sex institutions, which could demonstrate that their institution does not compromise necessarily gender equality in substance or outcomes.
Here again, no provision addresses the issue of public funding for single-sex education. Each State remains free to decide whether it wishes to finance SSE or to withhold such funding.
III. National Framework
The situation of single-sex education varies significantly from one country to another, each presenting its own particularities. It would neither be feasible nor appropriate to examine all existing systems in detail. Therefore, this analysis will focus specifically on the cases of the United States and Spain. The former has been presented as one of the most prominent examples of a country with single-sex education; however, the actual scope for implementing SSE in public schools depends on the interplay between federal regulations, judicial interpretation, and state-level education policies. The latter has undergone two major educational reforms in the past decade—both of which addressed the issue of SSE—prompting the Spanish Constitutional Court to take a position on the constitutionality of public funding for such models.
1. United States
A. Regulation
Historically, the 1972 Title IX federal law prohibited sex discrimination in publicly funded educational programs, leading many public schools to transition to coeducational models. This framework changed with the enactment of the Child Left Behind (NCLB) Act of 2001/2002, which relaxed Title IX’s implementing regulations and allowed public school districts to establish single-sex classes or schools if they considered such programs to be “in the best interest of their students”. This flexibility was intended to allow for innovative programs aimed at improving student performance.
However, it was not until 2006 that the U.S. Department of Education established strict requirements for public schools implementing single-sex education programs, primarily focused on ensuring non-discrimination and parental freedom. These regulations established three key safeguards:
- Voluntary enrollment: Participation in single-sex school must be absolute and completely voluntary for parents and students. They must receive clear information about the program and give explicit consent. Thus, their silence or passivity cannot be interpreted as acceptance.
- Substantial equality and alternative offerings: If a school district offers a single-sex school or class, it must provide a substantially equal coeducational alternative in the same subject or activity. This equality is assessed by factors including, but not limited to, admission criteria, curriculum, facilities, and staff qualifications, and disciplinary policies.
- Educational justification: Implementation must be based on a “reasonable motive” that justifies the program, such as the need for academic improvements due to high failure rates or discipline problems, and must be periodically evaluated.
Although these regulations remain formally in force, recent federal case law has raised significant obstacles to the practical implementation of SSE in public schools, as illustrated by Doe v. Vermilion Parish School Board (2011), and A.N.A. v. Breckinridge County Board of Education (2012). Thus, while the regulatory framework is permissive in theory, the scope for implementing public SSE has become increasingly limited in practice.
B. Exception for religious schools
Religious schools that receive federal funds are generally subject to Title IX unless they claim a religious exemption. Under 34 CFR § 106.12, a religious organization may request exemption from provisions of Title IX if compliance would conflict with its religious tenets. This exception requires two conditions: (1) the institution must be controlled by a religious organization; and (2) the challenged requirement must be inconsistent with its religious doctrine. This includes rules on sex-based separation.
Nevertheless, this exemption applies only to Title IX. Religious schools remain subject to state laws, many of which impose stricter anti-discrimination requirements or exclude SSE from eligibility for public funding. Therefore, a religious school may be exempt from federal obligation but still barred from offering SSE if state law conditions public funding on coeducation. In that case, it could legally operate, but it would not be entitled to public funding.
2. Spain
The central legal controversy in Spain has consistently focused on whether SSE schools should receive public funding (concerts), rather than the absolute legality of the model itself, which is generally uncontested in the private sphere.
For decades in Spain, the permissibility of SSE was derived from the lack of explicit prohibition in early educational laws and the interpretation that coeducation was a means – though not the only means – to promote the elimination of gender inequality.
In 2013 the Parliament passed a law which explicitly stated that SSE did not constitute discrimination – if UNESCO 1960 criteria were met – and prohibited unfavorable treatment in the granting of concerts. The Spanish Constitutional Court (SCC), subsequently confirmed that if the pedagogical model is constitutional, it cannot be excluded from public funding in conditions of equality (Decision 31/2018).
However, in 2020, the Spanish Parliament enacted a new law that prohibited public funding for single-sex education (SSE) centers that separate students by gender. In its Decision 34/2023, the SCC validated this refusal of public funding to SSE schools, since it affirmed that the denial of financing constitutes a “legitimate political option” of the legislature. The legislator has an ample margin of discretion to decide which educational models to support, and the denial of funds is seen as consistent with the State’s duty to remove obstacles to real equality (Art. 9.2 Spanish Constitution, SC).
Therefore, it could be said that the question of whether to permit or exclude public funding for SSE ultimately depends on the policy direction chosen by the ordinary legislator. It should also be noted that regional authorities cannot go beyond the framework established by the national legislation, and the last two national education reforms illustrate this clearly: they neither allowed regions to bar funding for SSE when it was guaranteed nor to permit it when the national law prohibited it.
In Spain, the legislation does not establish any exceptions for religious schools, so the same framework applies uniformly.
IV. Some Questions
Does separating students by sex inherently violate principles of gender equality, or can it be justified pedagogically and legally under certain conditions?
How should states assess whether single-sex schooling promotes or undermines inclusion and equal opportunity?
Is the freedom to choose single-sex education part of the broader right to educational freedom protected under constitutional or international law?
If a state chooses not to fund single-sex education, does it violate parental rights or principles of educational pluralism?
Should the legal assessment of public funding for SSE differ when the provider is a religious institution?
[i] Rose, L., Pierce, M., Dale, J., Miller, I. and Zong, L. (2023). Single-Sex Education. The Georgetown Journal of Gender and the Law, 24 (2), 787-809.