Diversity is a reality in Europe, and the European Union has adopted a variety of policies to promote equity, diversity, and inclusion, such as in the areas of social rights, employment, and education. Regarding the latter, policies are based on the belief that all learners, regardless of their background, should have the opportunity to reach their full potential.

One key policy is the European Pillar of Social Rights, adopted in 2017. The Pillar includes a number of provisions related to education, including the right to quality and inclusive education for all. The Recommendation of the Council on Promoting Common Values, Inclusive Education and the European Dimension of Teaching (2018) calls on Member States to take steps to ensure that all students have access to quality, inclusive education.

Finally, the European Child Guarantee (2022) is also relevant to the promotion of diversity and inclusion in education. The Guarantee aims to ensure that all children have access to the services they need to thrive, including education.

The notion of equity is a fundamental aspect of education and educational research, and its understanding is far from stable or universal. There is a lack of a universally accepted definition not only across scientific disciplines but also within educational science. Indeed, the concept of equity in education is a multifaceted one, shaped by a variety of social, political, and philosophical considerations. By examining the diverse perspectives, theoretical frameworks and research results that inform equity research, we can gain a deeper understanding of this concept and develop more effective strategies to promote equitable educational opportunities for all students. 

The central research questions guiding this study are: What are the conceptualizations and understandings (theoretical approaches) of "equity" within the realm of school education? What methodological approaches can be found in the way educational equity is measured in school education? To answer this question, the study aims to investigate the diverse directions that researchers take when engaging in equity research within school education through to an extensive systematic literature review.

The primary objective of this research is to provide an in-depth analysis of the evolving landscape of equity research within educational science through a literature review. The study will critically examine trends, methodologies, and theoretical frameworks employed by researchers to conceptualize equity. By understanding the diverse approaches taken by scholars in this field, the research aims to contribute valuable insights that can inform future discussions and policy considerations related to equity in education.

The study adopts a conceptual and theoretical framework that critically examines various perspectives on equity within education. Drawing from influential theories such as Rawls (1971), that proposed a theory of justice that emphasizes fairness and equal opportunity, suggesting that society should arrange institutions so that the least advantaged members benefit the most. Moreover, Sen (2009) introduced the concept of capabilities, emphasizing the ability to pursue one's goals and live a fulfilling life, while Nussbaum (2006) developed a list of ten central human capabilities that should be protected and promoted for all individuals. In addition, the recognition theory (see e.g, scholars like Stojanov, 2007), highlights the importance of addressing social hierarchies and power imbalances that can hinder equitable outcomes. Finally, intersectional approaches, promoted by scholars like Crenshaw (1991), emphasize the simultaneous effects of multiple identities, such as race, gender, and social class, on individuals' experiences and equal opportunities.

The aim of this systematic literature review (Newman & Gough, 2020) is to shed light on the nuanced ways in which equity is conceptualized and is perceived in the contemporary world. In planning, defining exclusion criteria, conducting, and reporting, we meticulously followed the PRISMA 2020 flow diagram (Page et al., 2020). Our research examined publications from the databases Education Source, ERIC, Scopus, and Web of Science within the specified timeframe (2019 – 2023). The analysis encompassed three distinct levels. The first level focused on the identification of records from the four databases (N = 3560). Records were removed before the screening for different reasons, including duplications, papers from journals with non-educational focus, and papers in other languages. During the second step, the screening, further papers were excluded through the study of the title and the abstract. The papers included in the review served to answer the research questions.

The expected outcomes of this paper provide an in-depth examination of the complexities surrounding the concepts of social equity and educational equity. They highlight the distinctions and ambivalences that exist between these two interrelated domains, emphasizing the need for a nuanced understanding of equity that encompass both social and educational dimensions. By providing a clear articulation of the conceptual distinctions between social equity and educational equity, the paper offers researchers a potential direction for further exploration and development of these concepts. Additionally, by addressing the postcolonial and decolonial implications of equity, it encourages scholars to adopt a more critical and reflective approach to their research endeavours. Finally, this comprehensive review not only enhances theoretical frameworks but also offers valuable considerations for practical applications within the field. This would allow for a more holistic and inclusive approach to equity research, one that recognizes the diverse backgrounds, experiences and perspectives of individuals.

Council Recommendation (2018). Promoting common values, inclusive education, and the European dimension of teaching ST/9010/2018/INIT, OJ C 195, 7.6.2018. European Council, European Commission and European Parliament (2017). Interinstitutional proclamation on the European Pillar of Social Rights, 13129/17, Brussels. Newman, M., Gough, D. (2020). Systematic Reviews in Educational Research: Methodology, Perspectives and Application. In: Zawacki-Richter, O., Kerres, M., Bedenlier, S., Bond, M., Buntins, K. (eds), Systematic Reviews in Educational Research. Springer VS, Wiesbaden. https://doi.org/10.1007/978-3-658-27602-7_1 Nussbaum, M. C. (2006). Frontiers of Justice. Disability, Nationality, Species Membership. Belknap Press. Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ 2021;372:n71. doi: 10.1136/bmj.n71 Rawls, J. (1971). A Theory of Justice. Harvard University Press. Sen, A. (2009). The Idea of Justice. Penguin. Stojanov, K. (2007). Intersubjective Recognition and the Development of Propositional Thinking. Journal of Philosophy of Education, 1, pp. 75-93.