PLOS ONE respondent information. Participants in the study are vulnerable populations whose data, when combined, could become identifying due to indirect identifiers (such as ethnicity, location, etc.). Data request could be made to the University of Malaya Research Ethics Committee (UMREC, reference number: UM. TNC2/UMREC- 848) at umrec@um. edu.my for researchers who meet the criteria for access to confidential data. Researchers can also contact the corresponding author for further details on the study methods and analysis. As the prescribed period by the Ethics Committee all information collected for this study will be kept safely for a minimum period of 5 years. Once the recommended period has lapsed without the need for any further analysis and audits, all electronic data will be deleted. Funding: This research was funded by The Asia Pacific Observatory (APO) on Health Systems and Policies [grant number IF034-2020 awarded to Tharani Loganathan]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist. Undocumented: An examination of legal identity and education provision for children in Malaysia Introduction Education is a fundamental human right. The right of all children to free and compulsory education at the elementary and fundamental stages is affirmed in Article 26 of the Universal Declaration of Human Rights [1]. The Convention on the Rights of the Child (CRC) reiterates the right of all children to education on the basis of equal opportunity [2]. Malaysia has ratified the CRC. Yet, crucial reservations made to Article 28 paragraph 1 (a) have excluded non-citizen children from commitments towards universal education. Malaysia has a robust public education system funded by the government with standardised national curriculums and examinations. Public education offers free or highly subsidised education to citizens from preschool, primary, secondary, post-secondary and tertiary levels [3]. There are also private options available mainly in urban areas for those who can afford the higher school fees [4–6]. Most undocumented and non-citizen children are not able to enter public schools [7] and must rely on informal education in the form of alternative or community learning centres supported by civil society organisations, faith-based organisations, private donors and local communities [8,9]. In Malaysia, the terms ‘undocumented’, ‘non-citizen’, ‘migrant’ and ‘stateless’ are sometimes used interchangeably. According to the Malaysian Immigration Act 1959/63 (Act 155), low-wage migrant workers are unable to bring their families or form new families in Malaysia [10,11], thus all children of migrant workers in Malaysia, irrespective of their parent’s immigration status are irregular migrants. Also, Malaysia is not a signatory of the 1951 Convention relating to the Status of Refugees and its 1967 Protocol [12], nor has it ratified the 1954 Convention relating to the Status of Stateless Persons [13], or the 1961 Convention on the Reduction of Statelessness [14,15]. As a result, the immigration law does not distinguish between refugees, asylum-seekers, irregular migrants, undocumented or stateless persons, treating them as ‘illegal immigrants’[11]. As such they are unable to gain legal employment and are at risk of detention and deportation, while access to healthcare, education, and social protection is severely restricted [16–18]. This is problematic as the current system risks criminalising those in need of international protection as well as penalising those who find themselves in these situations beyond their control. Besides refugees and asylum-seekers who fall under the protection of the UNHCR in Malaysia [19], little is known about the other groups of undocumented children in Malaysia, often collectively referred to as the “invisible children” because of their exclusion from national databases. Thus, the scope and the complexity of educational exclusion in Malaysia may be underestimated [20–22]. According to the intersectionality theory, an individual’s experience is shaped by the multitude of ways they are positioned according to race or ethnicity, class, gender, age, citizenship, language, religion, sexuality, and (dis)ability [23–26]. Thus, we hypothesise that although undocumented children are treated similarly by the state, they are part of diverse groups that confer different status, privileges, and marginalisation. Education is an empowering right and an effective instrument for marginalised children to raise themselves out of poverty and fully participate in society [27–31]. Yet there remain gaps in our understanding of the diversity and commonalities within this hidden population of marginalised children and their vulnerabilities in education access. As such, this paper aims to define, describe, and contextualise the different groups of undocumented children in Malaysia and their access to education. PLOS ONE | https://doi.org/10.1371/journal.pone.0263404 February 2, 2022 2 / 26